Hi Colin,
Well, I think I've found the problem. I stuck a 3.15A fuse in, but removed the brushes so I could measure a few voltages, without me damaging the windings.
As expected there was 240v across the brush connectors, and also as expected there was about 110 - 115v between the stator itself and each of the brushes, which confirms the connections with 2 of the caps as we expected.
At this point, while I am sitting there stroking my chin and having a think ...... BANG ! the condensor unit produces a nice blue spark and the fuse pops. Now the condensor has a nice black burn at one end.
So, I take out a knife and start to dissect the condensor. This surprised me. I was expecting some discrete components which had been potted, but no. I peel off the thin plastic outer cover, and I'm imediately into peeling away paper / metal layers like peeling an onion. Yes, it looks like a bespoke capacitor arrangement. No wonder the replacement is so expensive.
Eventually, I find a metal strip between the mains i/p and o/p on both the live and neutral connections so I'm pretty sure the connections were just as you suggested earlier on.
So, I am going to get myself some discrete caps and connect them up and give it a whirl. Hopefully I wont blow it (or myself) up !
Thanks very much for your guidance on this. Much appreciated. And it was nice to blow off my electronics cobwebs and get back on the tools.
Cheers
Simon