Push one bearing to the shell of the idler wheel. Using a bolt as an alignment guide, put a precision washer between two bearings and push a the second bearing to the shell as well. Remove bolt. Do this to all idler wheels; you will end up with twelve of these:
- 625-2RS bearing x 2
- precision shim washer
- idler wheel shell
Do not mix precision washers with regular M5 washers!