OK. I think you can measure a varying voltage at lug 2 (or the middle pad ) of the Rate pot (P1). If so, Measure the voltage at any of the Gates of Q1-Q4. IF the voltage is steady there, slowly adjust the Trimmer. At some point , you should see the voltage at the gate start to vary. Adjust the trimmer to get the maximum variance. Now you should hear phasing with a guitar signal applied. If not, tell us where you lost the varying voltage.