I admit the pattern looks a little

I admit the pattern looks a little strange. Anyhow our shop floor would not have let it pass if it had not worked in test. The correct shaft position is 90 mm from beams end and 90mm from the middle.The alignment between top and bottom is not the reason for the observed issues!Details: For the bottom bearing it can only move what is between the screw size and the bearing housings bore. That is average +/- 2mm. In the below picture, the position of the bottom bearing is just moved to the outmost right position, but that’s fully ok. No issue from that.The motor bracket is mounted not to the beam flange but to the vertical part. The position of the vertical part of the beam towards the rails may vary from the beam production. That’s why this bracket is adjustable, The only necessary adjustment is to have the motor shaft vertical to the carriage (the rails) and 90mm from the middle. This adjustment is needed to have the top belt running smooth. It allows +/2mm from the theoretic middle. It can be adjusted without the bottom shaft mounted.Connecting the bottom shaft to the top wheel with the elastic coupling allows both to be misaligned by +/-1 degree. With the distance between top and bottom bearings this 1 degree makes +/- 19 mm of admissible difference. That is more than can happen from production, thus it does not need special care.Top / bottom alignment is not the reason for damages on the motor or the clutch. The damage on the clutch was because it moved vertically.Also the issues with the positioning show, that the bottom clamping in the clutch was not tight and allowed the bottom shaft to slip vs the top sprocket.The reason for damages on the motor is in the top arm only. Belt tension and the shaft being vertical to the carriage is the only topics. The design with the elastic coupling is from 1995 and has proven reliable since then.