Interesting, I wonder if they'll recondition a Zenith 30IZ -as the parts required, diaphragms etc. seem to be unavailable. I've acquired a spare 30IZ from a Reliant, but with no diaphragms or float. £35.00 seemed reasonable a as flat price plus parts but per hour, it could spiral. Might give them a buzz though. A one-off fix though does not provide a long-term solution.
I still have a very rich running motor and a slightly leaky accelerator pump diaphragm, and though I've never removed it for a proper look-see, visible at the edge of the insulator between carb and manifold is a crack in that insulator which looks to have been repaired previously with epoxy resin or similar. I think fitting a Stomberg is the way to go, my questions include: will a single Stromberg CD150 fit onto the existing inlet manifold? Then will the existing throttle linkage and choke cable be adaptable to the new carb, and then there's finding a suitable air filter housing to consider. Wish I'd never seen this thread.