I have a somewhat similar problem with a GVP 040 in my A2000. It has always worked fine with the 4 meg that I originally purchased with it. But last year I purchased an additional 12 meg, and I can't get it to recognize all 16 meg (I checked the jumper options). I got it to recognize 12 meg at one point. I cleaned the contacts on the SIMM's and sockets, and eventually lost ground to where it will now only see 8 meg total out of the 16.
Besides the fact that it's a PITA to fuss with, I'm worried that du to the age of the equipment, that I will damage something by repeatedly installing and reinstalling components.
