Paul you are a Star. I have finally rebuilt the old girl and I have posted some pictures.
BTW You are bang on about the door opener. It went years ago and my wife used to consider having to use a knife to open the door as an endearing idiosyncrasy. The powder drawer is still OK though.
As you can see the backplate has has a hard life. Lots of corrosion, mainly around the lower half of course. I smeared Araldite all around the mating face and then assembled with a new gasket, topped up with acrylic sealant just to be sure.
I luck to have a great little shop near me which specializes in domestic appliance spares. The guy said he thought he'd never sell this kit 'cos it was so old .
This was full of gunk and s**t. I cleaned it out using water and ... a handful of black pepper corns. Anything would do as long as it's small and roughly spherical. Shake it all about and agitate / loosen the crud. Worked a treat.