I wouldn't mess with the socket connectors unless you definitely know there is a bad contact.
Well, it's quite obvious, isn't it:
When I startup the miggy, sometimes I just get a grey screen, with no change in brightness of the power LED (only the CAPS led blinks at each reset). When I push the BPPC a bit tighter to the expansionboard connector, the machine boots normally.
I had exactly the same problems and could reproduce them easily by changing the angles of the BPPC slightly. In some positions, my Miggy didn't boot at all, with others, it worked fine. A typical example of bad contact. The connectors get worn out after some time and loose their tight fit.