I have been having problem keeping my belts tight and the pressure rolls handles staying on. I up-graded the fasteners on my system. For the servo motors I added a 3/16 X 3/4 fender washer, 1/4" Star lock washer and a Keps lock nut to the motor. This way I have grip into the MDF and the motor. For the Z-axis drive gear, I removed the 6-32 set screw and replace it with a 6-32 Head socket cap screw. This allow you to apply more torque when tightening down the screw.
Here is a pic with the fasteners and drive gear in place.

For the handles I replaced all the outer square 1/4-20 nuts with 1/4-20 thin body nylon lock nuts. I got all the hardware from ACE Hardware. . Sorry for the blurry Picture. And yes mount a PC with 320Gb hard driver with wireless card in the cabinet.
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I like the idea of the PC in the printer. Well done!