Forgot to say that I do not have an oscilloscope to measure the circuit.
I do not hope the CEM3382 is broken, for it is hard to find.
And if the correct adjustment is very important, I will try to do that first. The adjustment I ever have made, is to reduce the sine bleeding with four of those trimmers. Maybe I did something wrong then.
But today I scratched with a wooden stick all over the solder part, while the module was playing and discover a loose solder part. It was pin 7 from IC2/TL064 close to the Audio Input. That pin is connected with R15.
Fixing the connection only result in a louder sound.
Since my A126 has mostly ic's without a socket, it will take much time to replace them. But it is worthwhile. And I think it is always good to replace old components, for they say that they do not perform optimal anymore.
On the other hand, I always hated the bleeding sine of this module. If the upcoming new Freq Shifter has no bleeding I'll have one. Because a FS is special, it is very funny.