DISCLAIMER: There is no other purpose of this post but to avoid this happening to anyone and causing damage to their CPS3 board.
I strongly recommend and encourage everyone to replace the plastic stand-offs with the brass ones, I recently had a board shipped in the case and the bottom screws on the plastic stand-off fell apart and the board got loose in the case and got banged on all sides. The JAMMA connector got chipped off from one side and volume got broken as well. Luckily it still survived and is fully operational.
These are the ones I used (M3: 24mm): w/ M3 machine screws (on both top and bottom). Looks very sturidy now.