Hi
I had this problem on a Seeburg jukebox,it is a very common fault,an ex Seeburg engineer told me the fix.
If you look at the tormat unit under the record rack you will see a thick phono type cable
follow this cable to where it meets the mechanism control panel
you will find it conects via an RCA/phono plug
What happens is you get slight corrosion on this plug and socket (especially if the jukebox has been kept in a damp environment)
All you need to do is clean the plug up and perhaps squeeze it a bit to make sure of good contact.
If this doesn't fix it there is a good fault finding link below
http://www.flippers.com/Seeburg-trblshoot.html