HP-67 card reader problem (ctd)

[Marcel Samek]

This is somewhat of a continuation of this thread on the previous forums: HP-67 Card Reader Problem

After cleaning my drive I seemed to get better results, but I returned to it later and was still having problems. Today my battery started showing as weak and so I plugged the calculator into the wall to charge and it occurred to me to run some tests on the card reader when plugged in, because I had not tried that before. Amazingly - all worked consistently.

I feel like an idiot who spent a bunch of time chasing ghosts, but it appears that it is related to the power. (Success was probably dependent on the length of the pause between attempts?) Oddly, when searching if others have experienced this, there seems to be several mentions of people seeing exactly the opposite of my situation: not being able to get the card reader to work when plugged in, but working OK on batteries, especially low batteries.

Does this behavior (card reader works when plugged in but not on batteries) make sense or is it a symptom of a deeper problem? The calculator came with a new nicd battery pack. Is it possible that that is the root of the problem?