Ah Terry San! I see you are at one with the CamBam! Nice work! :rainfro:
I had a bit of an 'eppyfanny' whilst painting the ceiling. I wonder if you could somehow angle the pins so the inner point is lower (a bit like a shuttlecock) . That would make the thing try to sit at the lowest point. I think whats happening is because the pins are
all in the same plane, there's nothing preventing it sliding side to side. I think the 'open circuit syndrome' happens when the pins slide a bit and get stuck to the balls by friction. Shinnier pins would help too. Brass and drill shafts are too rough maybe. Another idea is to have a spring on each pin pushing it down, rather than one big spring.
Scanning today didn't go too well. I got a couple of open circuits and then my Z axis started missing steps. (I'd been playing with motor tuning, trying to get more speed ). I noticed my 5V pull up on the parallel port pin had fallen off too. Gonna try again tomorrow.