I refurbished the Battery Pack 82033A.
With a knife and a little saw I cut the pack into pieces.
From Amazon I bought NiMH rechargeable batteries. Type SubC, 1,2V, 3,0Ah.
After I arranged the new batteries properly in the battery housing, I glued the two halves together. Not very difficult.
For charging the packs I use the standard HP charger. Even after a heavy discharge of the battery the charging current was not larger than 200mA.
That's absolutely ok for this type of batteries.
The temperature of the device during charging (inside the device) was not hotter than a little warm, if even.
Maximum voltage I measured after an overnight charging session was 5.4 Volts. Excellent!
My Printer and Cassette Drive work now very reliable and with the new much higher capacity of the batteries "Low Power" is not an issue any longer.
I posted a bit more detailed description including photos on my homepage. (best occasion to improve your German) http://www.schwalvenberg.com/de/hp-41cx/111-hp-82033a-battery-packs-akku
I invested some time to translate the article about the battery pack refurbishment (and others) into English and put it online. Just in case someone wants to see some details.http://www.schwalvenberg.com/en/hp-41cx/115-hp-82033a-battery-pack-refurbishment