OBERHEIM SYNTH

hi all.  we've had an OB-8 in the studio for years and it's been non-working, we decided to 
get it back up to spec.  the battery had fried/died years ago, so we replaced it (not easy!) 
it makes no sounds, so i bought an oberheim programs data cassette.  then the manual 
calls for a certain type of old tape deck and mini cables so i got those. 

all hooked up and won't load the sounds.  i can hear the data signal through the OB-8's 
output, so i know it's going in and the OB-8 will output sound.

then i noticed the "cassette enable" switch did not do what it's supposed to, which is turn 
off all lights and turn on the "cassette" light, meaning it's in that mode.  

anyone suggest a simple thing that might need to be done, as far as the switch?  our 
bandmate who de-soldered and re-soldered the battery is a bit techy so just throw any 
knowledge my way please.