That's all a bit confusing. Are you saying that you charged Duracells for 15 hours ? Or you started with NiCds and then changed to Duracells ? If so how many and what type ?

Anyway with the way your TX meter is behaving I'd guess that your Tx battery is bad so changing the Rx battery won't do anything.

It is quite easy to damage a crystal by dropping it but it either works or not. If this is the Tx crystal you mean (there's one in the Rx too) the Tx will not transmit at all if it is damaged so that fact that yours works for 5 minutes suggests that the crystal is not the problem.

Steve