Bryston 4B Power Amp not ST or SST

My recently acquired Bryston might have some issues with it.
For example there is a slight hum coming through the speakers and the green led lights are not right.

LED's are solid green when no music is playing, but turn to a constant flashing green the moment sound goes through it.

Also, when tapedeck is selected on the PRE and no sound is playing, if I turn the PRE's volume control to approx 2 o'clock the green light start to flash again. If I repeat this but with the PRE selected to CD player it doesn't flash green. It always flashes green on all pre selections when music is played.

Finally, when turned on, but not playing anything the casing is noticably warm - is this normal too.

Thanks in advance

Mark