Two empeg units are upgraded now. With the first one I followed the manual as is. When I tested the unit, it didn't work (the memory test failed). The problem turned out to be incomplete solder joints in some daugher board holes.
With the second unit I found a better solution that solves two problems:
1) Board alignment
2) Complete solder joints (first time - every time)
The way to get it would be to melt some solder on just those pads that connect to daughter board. I created small semi-circlular balls on each of these pads. This way the board aligns naturally (of course I still have to hold it in place, but now it doesn't shift) and I don't have to do a lot of solder "mixing" inside the connection hole to make a perfect connection.
Patrick, if you could put this tip into the manual, that'll be great.