I'm hoping someone can help an electronic ignoramus.  Here's the story.  I have a hundred and fifty open reel tapes I recorded twenty five years ago that I've been trying to digitize.  Most are field recordings I made on a Nagra on loan from the American Folklife Center or on a Revox B77 (I'm unsure of the exact model number) owned by a then brand new public radio station in Fort Wayne.  The restof the tapes are the 26 one-hour radio shows I produced using my field recordings.  After that gig ran it's course, I was left with the tapes and no machine.  The original field recordings are in the Archives of Traditional Music at Indiana University, and what I have are earliest copies dubbed on the ATM's Ampex decks.

Fast forward twenty years and I bought a Revox A77 on eBay and started dubbing my field tapes in my spare time.  Somewhere along the way my preschool daughter filched a light bulb out the Revox--I don't know what you call it but it was for a light activated shutoff.  I took the Revox to 20th Century Stereo on the north side.  The elderly European-accented proprietor ended doing $300 worth of repairs and adjustments.  This was two years ago, and I'm just now getting back to dubbing my tapes.  

But they don't sound the same.  I don't have the technical vocabulary to describe the sound difference.  The clarity is gone.  It sounds like my recordings have gone through some sort of filter that distances the sound.  Another description:  
the loss of clarity sounds like what happens when you dub cassettes on cheap portable decks from 1980.

Can anybody offer any help?   Like what kind of words I should use if I take it back to the old German guy.  Or do you know any other good repairman (or woman) in the Chicago area I could consult. 

Thank you
Paul Tyler