I bought some M4 machine screws, one m4 nut. For tools you need some painters tape to draw lines an dot for drill hole, drill, drill bit correct size for M4 hole, and a tap to make the tread in the hole.
I added one to my TDC it keeps the screw tighter and from un-adjusting after each shot. I also glued a nut on top of the barrel to give more support instead of putting allot of stress on the tapped treads if bumped while on the field. Its painted in this photo so might be hard to see it.
This mod increased my range, was able to hop any heavy weight bb's, and consistency. Was like night and day so easy to do too. It fixes the problem with the stock adjustment lever applying the wrong angle of hop which causes right hooking.
Yes it eliminated the wobble in the arm in the hop up unit. I would recommend it as its fairly cheap if not the stock arm should do, but keep in mind you are going to apply more pressure with the TDC. Also make sure you shim your plastic arm if you go that route.