My( Original) Phase 90 Block Logo Sounds "Weak"

[tonemonster]

I'm the original owner, and haven't used it much in recent years.  The jacks and pot are clean, and the battery is fresh. When used, it sounds a bit weak in the the degree of  phasing/amplitude? , and  frequency response.  Transistor prob? Does anyone have an original schematic, and or (better still) values for the components?

[Melanhead]

IIRC there's a trimpot in there that you can adjust for FET bias ... that might help. Just make note of where it was originally before playing around.

there's a schematic at www.geofex.com