Finally had a look at the beggar this weekend (all my fettling time has been consumed by the Wee SR125, now sorted, and the wife's car ....). Ball & spring a bit rusty, but a good soak in WD40 and a quick greasing restored bounce, however the ball still locks in position in the wee hole - looks like the hole has deepened through wear over the years and it's now just enough to hang onto the ball. So I popped out the spring and slapped in a weaker one (from a biro, OK?) - seems to be a bit better, but I'll have to monitor it for floppiness, can't have the lever banging my knee on every right-hander, can I?
I'll give it a couple of weeks to see how things go, then if it proves unworkable .... still got that nice one GC?
Thanks all.