Hi.
There are some interesting observations on corrosion caused by Nicads in vintage calculators.
https://www.rskey.org/CMS/index.php/the-library/42
As I mentioned in an earlier post, quite often there's no obvious leakage from NiCads but the corrosion can be quite severe in some cases. I had a suspicion that old NiCads may outgas corrosive gases.
Regards,
Symon