<p>Sorry to reply so late!. I did not find a solution but Contax service in Spain was open to fix the problem, for a modest fee of about 500 USD!. <br>
So, I still have the problem and probably never will fix it. I remove batteries when storing the camera and that is all.<br>
I own some more Contax bodies, in particular two RTS-I which are in working state. One of these is a RTS Gold 50 Anniversary, of course without any use (btw, I tried to sell it some years ago, without much success). <br>
The rarest I own is a Hewlett Packard 139, made by Contax for a HP plotter device. It is a Contax 139 with some modifications. <br>
Thanks for your answer.</p>