70's SB12 OT wiring

[freeformfx]

I"ve tried reversing the plate leads already but nothing on the secondary side. Which Im just wondering if I have right. and with the NFB disconnected even there is a lower volume distortion. Should I troubleshoot this with the NFB disconnected
I've suspected a bad tone module since most of the symptoms coincide with the treble control pot being turned from full CW to CCW.
thanks