Just changed the memory battery in my Cambridge model 20 GPS recorders.
No big deal, Rex who the Cambridge dealer at Williams Soaring showed me
how:

+ Purchase new batteries #2325 from local drug store/ radio shack.

+ Power up your GPS in order not to lose memory and security.

+ Remove 2 screws that hold antenna.

+ Under antenna you will see the battery, hold clip up and slide old
battery out.

+ Slip new battery in (+ up)

+ Replace antenna and screws.

Now that wasn't all that hard, was it? I used a small screw driver to
hold the retaining clip up, it would be a good idea to NOT touch the
case with any tool used to remove the battery. Case is probably
negative and we're working on the positive side of the battery. If you
get a spark followed by a puff of smoke------------------------I have
found the only way to get that little puff of smoke back inside the
little black box is to send it back to the factory.

Enjoy,
JJ
PS, My memory battery now reads 3.3 Volts, not its normal 2.8

PS #2, A day was lost at the standard nats this year because of "No
Trace"