Sire Z3 pot replacement?

[wjoyce]

I've had a Z3 for a while, and the pots are clearly where they managed to save some money.  The centre detents that we're poor to begin with have all but disappeared now, so I'd like to replace them.

So, what should I be looking out for - Brands, types, tips etc?  Has anybody seen a wiring schematic for this model of preamp?

EDIT : Sorry, meant to post in "Repairs and Technical" - could a mod please move?

Edited 3 hours ago by wjoyce

[wjoyce]

I've just had the control plate off, and all EQ pots are B50K, with the bass pot also being push-pull.  Need to find good quality replacements.