Originally Posted by suzukipro

Make sure you coat the setscrew threads (I'd stick with blue Loctite) and then tighten it in the pinion using a good allen/hex wrench. Loctite came and did a demo at my place of employment and the tech stated that it hardens when there is an absence of air, I'd make sure to let it sit long enough to harden up. The other thing to look at would be the mesh for the pinion & spur gears, hopefully not too loose / not too tight. Sometimes people use a piece of paper between the two gears to set the mesh depth correctly.