Turns out that the reservoir only LOOKED full! There was a kind of high water mark that tricked the eye, while the reservoir itself was empty because of leaks- the right rear caliper needed to be replaced and the right front caliper was rebuilt, and the system bled (of course). The master cylinder is just fine.
If anyone had a read through all the posts i've contributed to this site, i've done my fair share of 'pretty average' shyte (including f*king up spark plug threads, not connecting the starter motor earth strap on re-connection and spending another 3-4hrs ripping it out and changing it when i didn't need to)
But dude, something like assuming the resevoir is full by looking at the outside is up there with them! ...gotta get your hands dirty dude, which means caps come off!
Have you been hanging out with George W there in D.C.?
All in jest dude, just takin' the pi$$.
Glad it's all working well now mate.
Cam.
