Rear wiper & Headlamp W/W not working

Now, before everyone goes DOH! :doh:, yes, I have done a search for the above problems, but find the info somewhat confusing. The rear wiper is generally not responding, it did wipe for the length of my drive (100 feet), but then refuses to wipe anymore and the squirty things at the front are dry.

Before I start to poke around and do lots of damage are there any pointers? Have found the main fuse box with it's attendant spaghetti. I do not have a wiring diagram, so will be working blind.

It's a 1997 Disco XS 300 Tdi.

Any help gratefully received. Philip

For info, and this did catch me out, the rear wipers will not work if a door is open.

Also, the headlight wash only works when the lights are on.