HP-41CV Card Reader "Memory Lost"

[fpatton]

Hello!

TL;DR - Both before and after replacing the gummy wheel in a card reader of unknown state (thanks to everyone on this forum for the amazing tutorials!), powering up the HP-41CV results in "Memory Lost" when I try to insert a card. I'm wondering if this is a known issue, and if so, how to fix it.

Full version -
I recently picked up a "parts-only" pack of a non-working HP-41CV, some modules, a nice case, and a card reader. I mainly wanted the modules to go with my 41CX, and figured the rest was gravy if I could get it working. The modules seem to be fine, so that's good.

Following excellent tutorials here and elsewhere, I fixed the calculator's various broken posts and it's fine now, too. (Hurray! Cost easily recovered.) However, that card reader...

I plugged the reader into my 41CX, powered it up, and tried to run a card through it. The calculator turned off, and it took removing the batteries and waiting several minutes before it would turn on. Panic! All was well, as it recovered, and I won't make that mistake again. However, the CV was a bit more expendable, so...

I figured it might be an overcurrent draw from the motor if the wheel was gummy, so followed tutorials here to recover it. I successfully replaced the wheel with some fuel tubing I had on hand, carefully checking the diameter against the recommended 005 O-rings. With the motor removed, the geared wheel spins freely on its axle, yet nicely pulls a card through. After careful reassembly, I still get the "Memory Lost" error, and occasionally some really screwy characters on the display.

So - am I out of luck with this reader? No big deal if so, but if it's repairable, I'd love to have a working card reader.

Thanks for reading this far!

Fred