Posts: 282
Threads: 46
Joined: Jul 2005
I had a similar problem with an HP11C I brought to upgrade my old HP10C recently - I just twisted the case very, very gently to solve the problem ... didn't need to disassemble it (and personally I wouldn't recommend disassembly unless you are comfortable with that sort of thing and have an anti-static mat and wrist strap as the chips in the HP calculators seem to be very susceptible to ESD - as I learnt that the hard way about 15 years ago).
Occasionally I find that a gentle twist is needed to get my older 34C and 32 (Spice) machines to work - but that is (I think) because both of them have the foam sandwich style PCB, and a slight twist has usually fixed any problems caused by poor contacts internally. I found that I can I avoid this sort of problem occurring with these machines by ensuring that I always use them on a horizontal, flat, hard surface - not in my hand or even on a mouse mat. This minimises any movement when using them which seems to help - but it does mean that they don't travel around in my briefcase anymore.