ITT schaub lorenz 6000 no sound

I appoligize I don't speak german.
But all info on ITT gear is in german.

I bought an ITT 6000, to replace my 5500 because of the space.

It had a problem when arrived, the TB button was used so much it didn't stick.

I tried to solve that by switching the mechanism from the mono button to the TB.

Fuses were also blown from the speakers.

So when It arrived It played TB if I kept the button pushed in.
One fuse was ok, the other one cracked. I replaced them.
I'm not sure if I replaced It with the correct fuses.
I don't understand german but is it 1,8A 20mm 250V


Anyway after replacing the button, and the fuses.

I never got any sound out of the speakers.

Radio plays nice using TB sending the signal to another amplifier.
Just no sound when I connect speakers to the unit itself.
No noise or something either. Like the muting button is pushed or I don't know.

It's not the end of the world, I only paid 20 euro's.
But the exterior is in mint condition.

It's sad to throw it away or something. It could be a minor or major problem.
My knowledge is limited too replacing fuses, and removing dust etc ...

I cleaned a 5500 without a problem.

But I have no idea what is the problem here ... maybe switching the button mechanism was a mistake.
Or something with the fuses. Or something else ...

Thanks if you know something otherwise, I'll let someone look at it.
I'm from Belgium, ITT is pretty rare here, that's why I ask here first.