Uli:
I am still using one with the original battery and a sticker on the side that says "replace battery in 2005". So, I would not worry too much about it.

David:
It might not be worth the cost & nuisance of the repair when you can buy these used so cheaply and just install a replacement. I just bought one for $280 USD (which included shipping) and there are several on www.segelflug.de at prices between 80 and 100 Euros. They can't be used in Europe anymore so there are many available.

ROY