Wurlitzer 3400: Low sound from channel A

Hello!
My name is Stefan, lives in Sweden and I bought a non-working Wurlitzer 3400 Statesman for a couple of years ago.
The lights came on when I tried to start it, but nothing happened and it was a loud humming from the speakers, so I decided to change all electrolytic capacitors in the amplifier.
Over the years I have restored the rest of the box, so now everything works but I have almost no sound from channel A in stereo mode.
When I change the switch on the amplifier to mono there is more sounds from the A channels speakers but it`s low and don´t sound "good" and the balance controll on the amplifier have no effect, it only makes channel B sound more or less.
I tried to change the wire to the speakers from A to B and the silent channel moved to the B speakers,so the problem is not in the speakers so it must be the amplifier.
I have an oscilloscope and the service manual for the box so I tried to follow the sound through the amplifier but I cant figure out the problem.

Hello Stefan

I think you should have the amplifier repaired by a professional. Repair attempts without the necessary expertise rarely lead to success, but can cause greater damage.

Best regards - charly49