One common problem I've had is with the holoprojectors.
|L3-G0 Lego Holoprojector|
Anyway, this is one place I have to Kragle. The narrow arms especially want to fall off, and the 1x1 rounds. The clips are free to move though, and the axle fits in a round hole that lets the entire HP move and be positioned.
Biggest problem was that one of the chargers failed. We made do, but fortunately Shorai replaced it under warranty.
At RCCC the slip ring that powers the dome lights also got disconnected at the plug, and shorted, blowing a fuse. So that needs repaired too.
Also a few misc parts form the feet. Left battery box isn't staying on very well.
Lastly one of the feet might be slipping. The RCCC convention center has nasty carpet.