Mechanical Window Regulator
 

I am investigating possible sources for the mechanical window regulator that was used from the 407 to the 410 and I'm wondering if anybody has already come up with a solution

The best match I can come up with is the regulator that was used on the Mk Ii Jaguar. The front, business end, looks identical but the rear end lacks the second counterbalance spring that was used on Bristols. It looks as though it might well be possible to graft the Jaguar front end onto the Bristol back end, as it's the front end, where the cogs are, that's failed.

But if you know of a better approach I'd be glad to hear of it

Window mech
 

Having earlier looked at changing from electric to the mechanical, I wondered what the chances of getting the lifters. Bristol had none, but I did not try Brian May. The inner panel of the would be different I think, but possible cut to suit the later electric system which uses a counterbalance mechanism- like a tape measure. This is at the front and the towards the rear there is an upright with a runner on the horizontal metal gall channel.

The Jaguar Mk Ii window regulators are relatively easily sourced via eBay, here in the UK, and "usable" is indeed what they are.