Unclemeaty

Chris, You could be right.

I'll try and check the brake line pressure before the calipers to rule them out - I'll take the calipers out of the loop. I'll have to come up with some adapters or bypass a line or so, but I dont see this being much trouble tapping in just before the calipers for a good test.

In google searching, seems either a restriction somewhere upstream or a faulty caliper are both culprits.