Wow your battery pack made back in the 90's is just starting to need updating now ! You had a good quality pack there!
Thing is other batteries in the pack may start to fade soon also.
I know I hate throwing away anything that still works so is there any markings on the pack, can you see anything printed on the individual cells?
The biggest question for the replacement for me, would they be Ni-Cad's or NiMh batteries. I would not really want to mix the two.
Its not a biggie but there has been much development in battery technology over the years so,
any battery you may buy, will most likely have a much larger capacity to carry on for longer (seen on the battery as a milliamp ratings)
I have seen other technicians replace just one cell (usually with a much higher capacity than the rest of the pack) in remote weather monitoring stations and they seem to work fine.
However if it were me and I could afford it. I would replace all 4 "C" cells with newer ones.
The increased milliamp hours just means that your machine (that has an already regulated ( so its safe) current draw)
will just go for much longer before needing a recharge ..
Sorry about the babble I just hope that it was some where near to topic
Good luck ..
