Morris Minor Owners Club

This was fun. Driving quite normally and the throttle got stuck open. Open the bonnet the cable moves freely, so the problem must be inside my carb (a single webber 45) ?
My mechanic has had a look and seems to know nothing, the problem is that it's intermitent.

Any advise very welcome. thanks~~

Frayed throttle cable would be my guess.
Are you relying on the butterfly return spring? ( I think Webbers have them).

There is a return spring inside the weber which could have broken/ gone weak. Its behind the little plate between the barrels

Check your cable routing. It may have had a non standard replacement cable that is causing a problem where it passes through the bulkhead.

Weber installations I have seen have twin return springs fitted externally.