I am doing a conversion from brushed slash to Rally and have run into a small problem. So, you remove the rear bumper from the slash with the bottom two screws (# 7035 - 2.5x14mm). Now that the bumper is gone, when I put the screws back in, they go in farther.
This causes the rear wheels to completely lock up!!! I back the screws out and the wheels turn again.

I guess I will add some washers, but, I am surprised no one else has run into this!?
I bought this as a used slash in rough shape. Could the previous owner have screwed up re-installing the rear differential? Is it time-consuming to take that out and re-install?

Also, there seems to be some resistance when rolling (powered off). I have another (new) stock slash VXL and there is about half as much resistance there.
The used Rally seems to run OK.

Thanks for any advice.