somafunk, you anywhere near the northern end of Derbyshire? I would happily nip a little way to give it a go, just to see if it fits as much as anything. That was what I was expecting to get if my mates universal (one of those cubes) one didn’t fit.
Trying to avoid attacking the edges of the piston with anything too agressive, but a jubilee clip might be worth a go, even if it is a bit of a faff.
timber, a grider disk spanner might be worth a go, might be about the right size. Not got a cone pin spanner.
Oh, and waderider, with the lack of info available, stripping it down and trying the mates universal cube thing was the only option over sending it to a garage. And this way I have a £60 budget for tools before there is no saving made 🙂
But I would like to make a saving, hence the hunt for a cheap set…