Built my first AR-15 went out shooting on Sunday and had a few failures to feed.

http://www.ar15.com/forums/t_3_4/683100_My_AR_15_first_Build_.html

While investigating the issue I have found I cannot turn the gas key at all, unable to remove it for service.

Stuck.

Anyone have some tips other then grabbing a set of channel locks?

+1 on the "tap" drill. Happened to a friend. Gas plug would not go into the release setting. A couple of thwacks with a rubber mallet and it unbound whatever was bound up.

Of course if you're running a hand guard over the gas block you'll have to take a moment to get it out of the way.

I went shooting today, and after several failures to feed, I thought I would adjust the gas plug.   To my surprise, there was no gas plug to be found. It must've blown out on my first shot  we all had a good laugh and spent the last hour looking for it.

I have the XLP installed on mine and I noticed that after a session at the range, the selector is hard to turn to different positions. I can't move it by hand. I have to use a wrench to move the selector. I think there is a lot of carbon build up and it may need cleaning more frequently that what the instructions recommend.

Your Gas Block needs to be perfectly level.  Without the spring, Gas Plug installed - the Rod should be able to slide back and forth with gravity alone.  Loosen the front screw completely, and the port screw a little and you will feel the Gas Plug loosen.  Put oil on everything (just a wipe should do), inside the Rod Cup too.  Use M-Pro-7 oil (easy to find), I prefer Gunslick oil.  Lock down the port screw forcefully (this is the important one).  Tighten the front screw a little more than hand tight (or until Gas Plug slides easy, stop if it gets sticky).