broken HP65...help!

[rias]

My son inserted a magcard in the reader, which I had firmly forbidden him to (since I assumed that the rubber wheel was in very poor condition...) I use this HP65 as a calculator only, and never use the magcards... Anyway, the calculator motor started, grabbed hold of the magcard that got stuck and there was a terrible squeek, as from a dying animal. He turned power off, and just with some force, pulled out the magcard backwards.

Now the calculator is far from dead, but totally crappy. Turning it on, you will get any random number/numbers in the display, flickering digits, sometimes even "counting fast upwards". But sometimes (one out of ten) it looks correct, and I can even enter a correct digit, sometimes two or more. Turning the calculator off/on and repeating this process, the behavior "improves" very, very slowly, and after 100 times I can actually enter many correct digits.

I have opened the HP, hoping to find some burned component, but nothing visually.
Also I am very good with electronics in general, fully equipped for replacing circuits (even surface mounted which of course we have not here).

Logically... I drew out an awful amount of current to the motor. Assuming the large chip doing the motor control / card reader stuff broke down, would this disrupt the "normal function" of the calculating functions?

So what are your thoughts? I have no schematics, and honestly very low knowledge of how the HP65 is built up. What DC voltage can I check, and where are the "> 3.6V voltages" generated? Is there any specific resistor/diode/capacitor the may have broken during this fatal seconds I described above?

Very thankful for all suggestions...
/Richard