Here is ur solution....put motor in ur slash.. Remove set screw get some lipstick or liquid paper put small amount on set screw end that touch's motor shaft.on 4pm (noon is flat spot on shaft)..set pinion so mess is as close to 100% as u can get I have seen many and getting them to 80% is a test.tighten set screw so it leave some mark on shaft.. take a fiber wheel loon ur dremel and put a small nick in shaft does not have to be a long flat spot jut a indent.. put motor back in and run it til u cook it (JK) use some 272 red locktite,(u'll need heat to get it off) Best TnT

Ok thanks a lot

So i should notch the non- flat area with my dremel and put my set screw on that new spot ????

only thank me when it works.. I know it will..also get a New setscrew if its 4-40 I have some killer star locks..

YES To last post Notch it small...

k i will give it a try ... i have to order some new set screws and pinions though so it might be a little while.

FST and Keck have those in stock.. what are the setscrew size??

Its a 3x4.. ace hardware-lowes-Homedepot all have these and any hobby store ..

Its the stock traxxas pinion size grub screw. I just ordered some pinions that came with some but for now on ill just go to the hardware store and get like 20 haha.