Technics HD81 system doing random things

Hi, I've just bought a used Technics HD81 system and i'm running my tv through it, it worked perfect for around 30 mins and then just threw a wobbley. the system changed to CD on its own and then kept skipping through the cd's, flicking random selection on and off, same with repeat and randomly played songs without me touching anything, the system was then jammed on the CD selection (it wouldn't change to radio aux or tape) but i couldn't open the CD tray, no matter what button i hit it just kept switching the random play on and off- even if i push a buton on the tape deck. Have you any idea whats wrong with it please.
Regards Brian