Commenting on Pete's need to adjust to partial load on his pump brought back bad memories of removing the rear plate, oil running all over the place, trying to find the tiny little screws to make the adjustment, then putting the plate back on being sure not to bugger the big o-ring seal, going for a test drive, then doing it all over again because I went too far or not far enough.
I have been thinking for a while about this and I am finally going to try a little R&D and see if I can drill a couple of small holes in the rear plate that can be closed with grommets. Then to make an adjustment, you would prise the grommets out, do your clicks on the adjuster, pop the grommets back in and be off on your test drive. The holes would also help position the screwdriver.
I have a couple of spare pumps I can try this on. Maybe I'll have a presento on this at PUB.
Cheers,
CT