I have a 509 that is almost impossible to get the mag to drop from due to having to rotate the gun so far to get the leverage to "bottom out" the mag release that the mag will get hung from pressure from the base of my palm, if you can "bottom it out."  I know that the guns have been out for a while. Is there a replacement part or aftermarket solution to the mag release issue (it works fine from the right side, but not the left).  I have searched but found no luck, so I thought that I would ask here.  TIA.

Very simple fix.

There is a folded piece of metal on the front of the magazine. This provides the ledge where the nipple of the magazine release sits. The magazine release pushes that nipple to one side, and off the ledge.

Take a small file and work on that folded piece of metal. It often slopes downward to one side. You can see how pushing the magazine release button would now have to travel farther and effectively push the magazine up to get it to release. File that ledge on the magazine so that it is at a right angle to the magazine body. Also, put a slight bevel at the corners.

Check your work often by testing the magazine in the gun. Go to far, and the magazine won’t lock into place or will fall out too easily.

I’ve done this for all my mags, and they are really slick to eject out of the gun now.