Fixing top slider and runner for rear passenger door

Hi everyone,

The rear passenger door is causing me real problems - the runner at the top is all bent and squished and the runner wheels pop out, leaving the door to hang off. It's then a nightmare to get back in and of course it doesn't

So I definitely need to fix this - as it's a camper I really need that door for access. I've got hold of a top hinge with the wheels but have a couple of Qs for anyone who's tried this fix before:

Anything I should know or words of wisdom before attacking it with a screwdriver?

Can it be done with the door still 'on' or should I try and unhinge it from the bottom too and fix it separate to the van?

Any tips for straightening the aluminium runner? It looks like a pain and not something you can replace.

Thanks everyone

Actually it's not aluminium. It's part of the roof section and it is not replaceable and almost impossible to get it straight again. It is a very poor design. I have cut roofs off and tried to get the rail off. But to no avail. It is spot welded on and trying to remove it even after drilling, the rail just gets bent to hell.

I have tried to sort them out with various bodywork tools on several vans and usually have to settle for a compromise. It is a job for the very patient and ingenious. Me? Ingenious, most definitely. Patient, most definitely not.