Drawmer DF330 Universal Filter schematic?

During a meeting with a sound engineer client today concerning his very late tax return (!!), I noticed a Drawmer DF330 in his equipment list, against which there was a note stating - "dead". When I asked him about this, he just said that it stopped working when on tour a few years back, and wasn't able to get hold of a service manual at the time because Drawmer had run out. Apparently he used it on a feed to a DAT recorder from the mixing desk.

Drawmer weren't at all helpful when I called them this afternoon - can anyone help out please with a schematic for the DF330, or better still the service manual.
Many thanks

Bit of a long shot I suppose.

Drawmer schems are as rare as unicorns
PSU I suspect...from memory these had a linear PSU ...should be an easy fix...!
Offer him £50 (ebay price for thisunit dead)...... after all its dead and scrap value.
Worth a punt IMHO.