YVRDAN

Hey Everybody, A couple of questions for the forum. I bought this guitar about 20 years ago and it's been hanging on my wall ever since. I bought it from a friend of my wife for about $700 as part of an estate sale. When I got it home I plugged it into an amp and it didn't sound good at all. So I popped off the cover and there was a 9 volt battery in there. Weird. I changed the battery and fired it up again and it sounded better but with way too much overdrive. I guess from the battery system? Not to my taste at all. So figuring I would look into it another time I hung it up and here we are! Aside from the occasional strum unplugged, I never plugged it in since. Was this a common modification back in the day? The previous owner was apparently into heavy rock so maybe he was trying to get overdrive without a pedal? Is this a relative easy fix to bring it back to stock? Would you trust the tech at the local guitar store to do this for you? My other question is about the age. It has a 6 digit serial number (393662) and says Made in the USA just below the number. I can see on one pot the numbers 028 and to the right R137. Its tough to see much else with the wires and solder. The other pots don't have anything visible to me. They have a layer of corrosion type white stuff coating them. The kind of stuff you get on the top of your car battery. Any info is really appreciated. Thanks, Dan