Best do a Charge-Discharge test (Cycle) on both.

Cycle 3 times and observe what the reading is at full discharge on the 3rd cycle.

If it is within 20 % of the packs rated capacity, it should be O.K. (i.e. on a 600 Ma/H Tx pack, if should come up at 480 Ma/H or more.)

If lower than that - replace it.

Also, check all the connection plugs for any greeny/blue powdery build up. If you find any, you have the start of the dreaded "Black Wire" syndrome. If so- ditch the pack and the connector and go get new ones.