For sure I'm having fun! :p
But now I am getting to a point that need some more directions...
I swapped out the suspicious transistor, but the problem is still there, and I do get the same behaviour when I poke it with an insulated tool.
In the attached picture, this is Q4.
I tried to trace the incoming signal on both channels. The difference I found is that the right channel leaves the emitter of the transistor (Q4 in the pic) with a DC level added to it, while this is not the case for the left channel. I mean the signal has no dc component after it leaves Q2.
Also, I took some measurements with respect to ground on Q1 which is the transistor that receives the power for the board.
Right channel: Vc= 25.4, Vb = 6.6, Ve = 6
Left channel: Vc = 25.4, Vb = 3.2, Ve = 0,69
As you can understand, I am confused, and i'm not sure what to look for.
All capacitors are measuring fine, and all resistors also are within limits.
I have the schematic of the system that I have found in another forum, but it is too blurry to understand and I think it is a little cropped. I am attaching it in case any of you can share some advice!
Thank you