sounds like the internal power supply is begining to fail m8, have you also had any issues with the motor moving, or receiving channels on horizontal polarity?
how handy are you with a screwdriver and soldering iron m8, as if its what i think it is, itll cost less than a quid to fix
the person who posted that theirs went faulty after turning it off, this is common with failing power supplies, theyll keep going untill theyre powered off, the capacitors discharge, then when theyre powered back on, the surge causes them to completley fail
if you lift the lid off the receiver, and look at the power supply board, youll see small 'cans' , if the tops of these are slightly bulging, thats your problem and they need replacing