PS. By the way, as i understood, the transformer was repaired.
What if the voltage feedback winding ( related to R215 2.7 Ohm) outputs were accidentally interchanged? Or power winding ( related to C218) outputs interchanged?
If this happened, the PSU will behave strangely and the output voltage will be different at different loads.
To fix it, it would be enough to cut the copper tracks from the winding and swap them

 

One more picture needed . T204 primary winding, secondary and feedback (related to R215 ) windings.
More load needed- speakers and steady input, say 1kHz at the amplifier input

PS. By the way, as i understood, the transformer was repaired.
What if the voltage feedback winding ( related to R215 2.7 Ohm) outputs were accidentally interchanged? Or power winding ( related to C218) outputs interchanged?
If this happened, the PSU will behave strangely and the output voltage will be different at different loads.
To fix it, it would be enough to cut the copper tracks from the winding and swap them

Sorry! I've not been at my house for a few days, I'll be back on the weekend so I can test this.
In short, I'll remove T203 and T204, hook up one of the coils to a 12vAC transformer, and put a load on all the other loads and scope them one at a time.
I expect this will tell me the direction and number of turns of each coil in relation to the first, right?
I'll also grab those pictures you mentioned on the first quote. I'll need to get creative and create a function generator somehow hehe.

Thanks again!