Re the contact problem in your Etrex:

I had the same problem (as have MANY others- Garmin has ignored the design issue) and solved it completely by stuffing a small piece of foam rubber in between the batteries above and below the central point where the mechanism for the back lock inserts. Doesn't take much- just two pieces about 1/2" long by 1/4" square. It may take a little experimentation to get it just right.

This is a simple, cheap and effective solution to an annoying problem.

On topic- I just bought some Duracell rechargeables, and they work just great with my Maha charger.

Rick