Well, I sent off to Venhill for a custom made hose (£32 delivered, bargain) and it was delivered today.
I just had the time to chuck it all randomly together and bleed, and, on a swift basic test, it seems to be fixed.
So it was the hose. I was right. (and that’s TWICE I’ve been right today, a record I think!)
Which was my first thought, before Modern Vespa forum led me to replace the master cylinder (£45) and STW led me to replace the calliper (£38)
I’m not annoyed. Really I’m not.
But by fek that’s the last time I listen to anybody else with anything mechanical! 😈
(I’m gonna pull the old hose apart and have a look inside. The old calliper and M/cyl are OK and I’ll sell them on.)