I am working on an HP-65 that I just purchased, already having rebuilt the battery pack and replaced the gummy wheel on the card reader (with thanks to Jeff & Victor). The cards seem to feed correctly now.
When I record a program it seems to work (switch to W/PRGM, display blanks as they feed through, then the display returns to what it was before). When I try to read a program it pulls the card through, the display blanks, but then it comes back with the flashing "0.00" and and the program memory cleared.
When I had it disected I cleaned everything, there were no obviously broken wires or connection, all gummy stuff was removed, the head was clean (now it's sparkling) and appeared to have no wear. Have attempted to do the reading / writing both on and off the charger both with a full and partial used battery.
The cards are new un-used HP-67/41 magnetic cards. I have no pre-recorded cards so I don't know if it is a write, read, or both problem.
If anyone has any suggestions on where to go from here I would really appreciate the help as I would love to have an operational card reader.