familiar with 6 slots, it is a good idea to secure the mounting posts between the top and bottom pcbs, it will improve reliability (not that its a big issue with these board sets imho). There was a good thread on this a while ago, im searching for it.
Aye, that's part of the problem. The pcbs were designed to be fastened semi-permanently inside a cab. We hobbyists handle them much more often than the designers originally intended. I've had some boards die on me I believe due to poor handling (even though I'm carefull with them, they're very fragile).