Beogram 6500 turntable - Sound failure

Can anyone help, the turntable all seems to he working fine, records play and I can just make out the sound as the record turns but there is no real sound of the music coming through the speakers. There is no problem with the sound quality through the speakers from the CD, Radio or Tape deck parts of the system. Many thanks for any advice.

Has it been unused for some time?

If so try playing a record and when the stylus has dropped leave it a second and then raise the tonearm do this a dozen times and see if it helps.