Becker Radio battery

Hi Guys,
I seem to remember that there was some discussion here a few years ago
about problems with the internal battery in Becker VHF Transceivers
going flat, and the radio subsequently losing stored frequencies and
other information.
A friend of mine has a Becker radio, which is starting to show signs
of such failure, and I am wondering if the battery is a readily
available type, and can be replaced by someone with some experience
with electronics (35 years working in the game).
TIA
Cheers, John G. (Melbourne, Australia)