Doepfer

haa!!! Cheetah ms6 and Kawai SX240... getting flashbacks to reading Keyboard magazine in the '80s! ;-)
but seriously (and relevant) - that is exactly what happened with my Regelwerk! it started going weird, figured it was the battery, opened it up, and lo and behold one of the battery contacts had corroded!! *most* fortunately the corrosion was only on the battery and hadn't migrated to the board yet, so replacing it was simple.

      From: "Analog Monster analogmonster@ymail.com [Doepfer_a100]" <Doepfer_a100@yahoogroups.com>
 To: Doepfer_a100@yahoogroups.com 
 Sent: Sunday, September 25, 2016 4:30 AM
 Subject: Re: [Doepfer_a100] Re: Regelwerk issues
   
    I say almost identical. I've just noticed it's got 3 pins not 2. Reichelt actually has the 3 pin in stock. If you have anything else a bit old it might be worth checking. Actually these batteries are notoriously an old synth destroyer. Cheetah ms6 (an oberheim matrix 6 clone) and the teisco/kawai  sx240 (analog DCO poly) are often found with corroded boards as these batteries have leaked.