Acoustic 470

[gbono]

Acoustic 470 which seems to have several issues. First off, the vibrato is bleeding though even with the intensity turned down and footswitch used to turn the feature off. You can just barely hear it audibly and it shows up on a scope modulating the input signal. I believe the feature is always "on" and the footswitch turns it off? 
Next problem and it's possibly related to the above issue, is that there is a residual distortion that can be heard especially after playing single notes.  Sounds like very mild crossover distortion.  The distortion pot is switched all the way off – switch engaged.  Sinewave input doesn't show crossover distortion at the output.
The preamp boards are a real pain to probe in the chassis since there are a few dozen wires soldered on the edge terminations and they like to break when moving the boards. Looking from the input onto the 170043 board, it looks like I shouldn't see a change in the signal comparing the outputs of Q102 and Q104 – that's my first measurement.  Any other ideas?