I started tumbling brass in my Harbor Freight tumbler late one day and it stopped tumbling sometime during the night. In the morning I found that some of my brass had some sort of whitish frost as shown by the picture. My best guess is that there is some sort of chemical reaction between the brass and the stainless pins (I use 1 LB of stainless pins, distilled water to about 1 inch from the top, 1/4 TSP Lemi-shine, 1/4 TSP Tide Cold Water, and about forty 8mm cases deprimed). Most of the brass does not have any frosting. The frosting is usually only on one side of the case. The two cases on the far left and far right have no frosting and were added for comparison. The 2nd from the right is the worst as most of one side is covered with the frost. The 2nd and 3rd from the left show what appears to be splotches caused by some pins. The frost cannot be rubbed off. Even Brasso has a hard time removing the frost. Perhaps the lesson learned is to remove the brass before the tumbling has stopped.
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One day I found my Harbor Freight tumbler had stopped turning and the motor was stalled and very hot. The drum nut had somehow unscrewed and jammed into the heat shield as shown by this picture.
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Perhaps I did not tighten the nut tight enough and it touched the red lip now and then causing it to unscrew. My solution to prevent this from happening again was to lift the nut up away from the red lip by using some duct tape on the idler roller as shown by this picture.
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A split lock washer of the appropriate size would keep your knob from backing off when tightened. I can't really help you with the frosting on the cases, have you tried a soak in water with some Lemi-shine in followed by a good rinse? I've seen a few guys on here say they will leave their drum full for a couple of hours with no problems.

I have been wet tumbling for a little while myself. I haven't heard of using Tide before. I have only used dish washing liquid and recently started using liquid car wash with wax in it. Maybe the tide is your problem with the frost. I have no idea about the nut coming loose on the tumbler.

FWIW My brass has always come out looking good. I would not let it sit in stagnate in the tumbler for very long ie to soak. I tumble, rinse, towel dry then put brass on trays in food dehydrator.

Why are you using Tide, the Lemishine and a teaspoon of Dawn works wonders.

Just my 2
Vince

The nut won't back off if tightened enough.  You need to adjust the plastic tabs that space the two cans away from the ends.  None of mine were adjusted properly.  I only had one nut back off and I know it was my fault.  

My two tumblers have done about 5000 cases so far and 7 batches ran this weekend, total 28 hours.  I don't run them at night and have them outside a sliding glass door where I can glance at them once in a while.

Stop using Tide.

Run a large magnet through your cases to be sure that there are no steel cases mixed in.  

1/4 tsp may be too much Lemishine.  A 1/2 to 3/4 9mm case full is all you need.

"In the morning I found that some of my brass"

Tumbling all night isn't necessary, 1 to 3 hours should do it.
1/4 tsp of Lemi-shine to a gallon of water. This amount depends on the hardness of your water.
Less than 1 tsp of Dawn dish detergent. You don't want a lot of bubbles.
Remove brass promptly and rinse in cold water, spread on a towel to dry.
I sometimes place the wet brass in a collander and try them with a heat gun.
Leaving the brass in the tumbling solution, longer than necessary, will allow the Lemi-shine to leach zinc from the brass.
This is what I found works for me.

Your tumbler frame is missing the two black tabs that prevent the drum from moving too far left and right.  That is also why you have the paint scraping in the left side of the frame in your picture.  I see the holes in the frame, but not the tabs.  I don't recall when I got mine if the tabs were installed or if they were in a little bag and I had to install them, but either way, yours are not there.

I just had a batch frost and it's a pain to clean after it happens.  Tumble in walnut for a few hours or re do the wet tumble.  I have also just put the stained batch in a bowl of clean water and added lemishine a little at a time, stir, add more lemishine, continue until the color changes back to gold.  Sometimes it works, but rinse them really well when done.  

As far as I know the frosting and staining it is from letting them sit in the water (see above post) - try to remove them as soon after the tumbling and rinse well so all that dirty water/crap/lemishine doesn't re stain the brass.

Thanks for all the comments.

Yes, my "lesson learned" concerning the frosting was to remove the brass as soon as possible after the tumbling. I use Tide as it has less suds. Dawn makes very thick suds that I don't like. They are both detergent and both do what needs to be done. If Tide is hard on brass then I would have had problems with the brass fly on my blue jeans - I don't. I would think that if the Tide or Lemi-shine caused the frosting then the frosting would have covered 100% of all cases. That did not happen. Only parts of some of the cases had frosting.

The harbor freight guides are plastic and mine wore down to nothing so I don't use them any more. I doubt the aluminum making the scratching on my HF will be wearing down the steel sides or the aluminum itself anytime soon. The nut problem only happened to me once. I assume I did not tighten it enough. Should I do that again my fix should prevent the nut from unscrewing.

If you are interested, take a look at the later pages of the wet tumbling on the cheap thread.  A poster (sorry, forgot who it was) showed his design for a 4" PVC drum that replaces the two supplied ones.  It only cost a few bucks and a few minutes of time to make, but it is a big improvement.  It will use the end walls to maintain alignment and there is only one nut, located on the exterior wall.

Most of all, it allows more brass in one container that keeps consistency in color - ever have two identical drums of brass come out different?  Secondly, the cap is a lot less inconvenient than the two caps, etc., of the factory drums.  I think it does a better overall job.

As an experiment I tumbled the same type of brass in Tide but with no Lemi-Shine for my normal 5 hours. I then left it "as is" overnight just as I had done before. There was no frost. The heat treat stain was still noticeable and the brass was not its normal brightness although it was clean with no powder residue. This proves the following: Tide does not cause frost. Lemi-Shine can cause frost if left to soak too long. Lemi-Shine removes heat treat stains and makes brass bright. Stainless pins does a great job removing crud both inside and outside of the cases but does not make brass bright.

After I sized and trimmed the brass I again tumbled the brass with stainless pins for 3 hours. I used 1/4 teaspoon of Tide and a half a 9mm case of Lemi-Shine as someone suggested. The brass lost the heat treat stains and was shiny bright. The water was somewhat black. Again this proves that Lemi-Shine removes heat treat stains and make brass bright. I would have thought that the first stainless pin cleaning would have removed all the black powder crud. I've noticed that Brasso and Nu-Finish react with brass causing a black compound visible on the cleaning cloth. Perhaps the Lemi-Shine does the same thing and the black is from a compound created by Lemi-Shine when it reacts with brass. It sure looks nice though.