I have a dozen NiCd that I purchase over 10 years ago and I'm just starting to have trouble with. I'm slowly replacing them with NiMh now, only drawback is I had to purchase a couple of new chargers for the NiMh.
Perhaps you just need to cycle the batteries and test them on your voltmeter, or take them to a local hobby shop that know how to do it for you.
- RCT