I am looking for a PTC thermistor, epoxy coated with approximately these
characteristics:
6.8k ohm at 45 degrees celsius

I have an old nicad battery pack with a thermistor that failed during
charging and one of the battery cells split along with the thermistor. The
thermistor is inside the battery pack and connected in series with the
charging circuit. The numbers on the thermistor are 6K8K. After searching
the internet I deduced that the numbers meant 6.8K ohm with 10 percent
tolerance. The 45 degrees celsius was the upper recommended
charging/operating temperature for the batter pack stated in the manual.

I took the battery pack to a Batteries Plus to rebuild it and their
suppliers could not find a replacement. I figured that this thermistor isn't
that unusual.

Maybe someone can suggest a replacement, at least an electronics store that
I can buy only one or two and not a hundred.