I shimmed the idlers with 2x 1mm washers. I think the idler is 2.5mm low but I could not find a 1/2mm washer. It aligns pretty well with 2mm. I also lifted up the stepper pulley 1/2mm up, it seemed a bit low at the prescribed 4mm from the tip of the stepper. You will also need screws that are 5mm longer for the idler pulleys.