Weird behavior HP41c

[Geoff Quickfall]

Does it only happen when the quad is in place? Is the calc stable without the quad in place? If so maybe a contact problem on the module. Ensure contact springs in module (visible) are not deformed. Perhaps an intermittent contact causing the partition to corrupt when calc is jiggled.

I have placed a drop of DeOxit gold or Red on the contacts of the module then plug and unplug a few times.