For your full auto business you need a new Cutoff lever
your is ground down to the point where its not catching anymore
Have u tried other mags or putting 1-2 drops of silicone into the mag
Also try this
Flash a flashlight down your magwell and look at the nozzle, fire in semi or full auto see if the nozzle returns far enough back so that you cant see it.
If it does go back far enough its your mag, Try KA or TM ones see if it makes a difference