@MrsBeanbag
My A1200+1260 had similar problem many years ago circa 2000.
I traced the problem to a loose fitting connection of the Apollo 1260 to the A1200 MB. The A1260 was at a slight angle due to gravitational attraction of a nearby planet (Earth).
Solution: Duct Tape! Once I taped it in such a way as to support the board in a perfectly straight line I never had a problem again. Its been 12 years and I never even had to replace the tape or or anything.