Technics RS-TR555. No sound?

Because of the digital age, this has not been used for a while. Yesterday I went to play a tape and it played fine - an hour later I went to play the same tape and there was no sound, and I notice that when I press play, the recording level LCD's go directly to their maximum, as though in the red. I have tried various tapes (even a blank one)and the same thing happens. I can usually get my head around these sort of issues but I've drawn a blank on this. Any thoughts?