I noticed in my Seeburg Entertainer (STD2) that the tone seemed to change randomly and that even with minimal treble there still seemed to be too much high frequencies. The problem was especially bad on worn records.
What I did:I decided to take off the pre-amplifier board and inspect the tone switches. Below is what I found.
I cleaned the switches up with a rubber eraser and some deoxit. (I forgot to take after photos)