I have been restoring a GF-9090 for some time, which I thought I had fully sorted but the sound from the tape deck seems distorted and what I can only describe as 'muddy'. The radio sounds perfect, and is so different from the tape playback.
So far, I have changed all belts and the idler tyre. I have also cleaned lubed the box mechanism, as well as deoxit the sliders and cleaned the head, capstan and record bar.
I was not keen on the box when first found it in terrible, but totally complete state. However, the longer I look at it, and the more I work on it, I am getting more and more attached to it and would love to see it fully working.
Having searched around this and other forums, I am getting the feeling it could be a capacitor / board issue but don't really want to embark on a cap changing mission unless one of you with more knowledge than me can suggest I need to go this way.