Procat belt adjustment

[AndyF]

Hi,

I have an old Procat that I used to race and got back running not so long back. It is virtually a std car except for kyosho gold shocks.

I can't get the belt to stay in the middle of the front diff pully. Everytime I adjust it with those screws at the front it either shoots off to the right or to the left. When I raced it many many moons ago I don't remember having these issue. Any ideas?