Beomaster 4400

Hi, I have acquired two Beomaster 4400.

One of the units which worked fully apart from the tuner which played finely and didn’t lock into any chanel. The fault is definitely in the tuner board as when I swapped it the tuner worked. When carrying out some audio tests through phono using an iPhone, the unit went into overload mode and since then the relay clicks and goes into overload mode.

The other unit, which has a much cleaner interior, only plays in mono. The left stereo channel is very faint in all settings. The same with headphones.

I have made some multimeter tests in line with a Beolover article:

Does anyone know what way I could progress with either units?

The second unit might not have suffered an output stage problem as there is audio from both channels albeit very low from the left channels ?