Could also be the mute switch in the deck!!!
Worth checking that first, before splashing out on a new cartridge.
Mute in the deck: Perhaps it can be exercised?
Agreed... consider my LINK to Soundsmith as research only... Don't spend any $ until your cartridge might be tested faulty.
Is the DIN line in good shape? Maybe something loose there?
Is the stylus guard completely out of the way -not contacting the record?
It seems like subtle bumps (door closing) can cause this...