Did they disturb the gasket between dynamo and housing by any chance?
Sorry, pressed wrong button! Dynamo gears will make a high-pitched whine if you reduce gasket thickness. But it wouldn't be intermittent. I've run SU fuel pumps for years and never heard a high pitched noise from them - they just tick gently when you turn the ignition on.
If disturbing the distributor made it go quiet even temporarily I'd suspect something in that area...
Sorry, pressed wrong button! Dynamo gears will make a high-pitched whine if you reduce gasket thickness. But it wouldn't be intermittent. I've run SU fuel pumps for years and never heard a high pitched noise from them - they just tick gently when you turn the ignition on.
If disturbing the distributor made it go quiet even temporarily I'd suspect something in that area...