Thanks to the info on here, BOP's wipers work as they should (slow, fast & variable delay) for the first time in my 11 year ownership

. This was the state it was in when I started:
I haven't had the motor apart, but have done everything else noted; de-greasing & re-greasing the mechanism & stripping the delay governor & replacing the non-existent foam. I also replaced the broken bobbin mountings with some I'd bought for this purpose many many years ago (how I found them again, I don't know!)
I still haven't worked out how you tighten the clamp screw in situ... (access is nigh on impossible).
It's all back in now. I couldn't get the delay to work properly at first even though I'd fixed the vacuum side of things. Not being a great one for car electrics, I was a bit stumped but by watching it operate I came to the conclusion that it wasn't working in the correct 'cycle'. The answer was that I'd got the yellow & purple wires the wrong way round

. This is now the correct way:

