For some one who seems to know electronics repair, I am surprised you aren't working with a grounded ESD mat on your bench and an ESD strap on your wrist !! The M100/102/200 use all MOS/CMOS I.C's. You are static damaging/weakening the main board as you keep handling it.
Granted that the devices were more static resistant in the 80's due to the larger die geometries used in the I.C's then, but proper ESD protection should always be used.
