Notes:
explain orientation of the y drive bracket
idler:
order of the plates
screw the plates to the frame first, the screws can't be inserted after the idler
attach the idler with the screws still a little bit loose to let the m5 through hole line up right with the m4 threaded hole
belt
orientation
length
verify alignment
use alignment jig for 1 linear rail and keep the other loosely screwed in!
get the two installed and configure the dual y motors + dual endstops. Test all of this with the belt clips hanging in the air to reduce the risk of damaging something as you test it
final picture