I managed to slip a 4mm rubber washer onto the lever pivot of the other caliper. The spring has to come off first. There is one place where you really have to squash the washer to get it through a 2mm gap but it seems to have survived. I packed some anti-corrosion grease in there too.
Unfortunately I had no time to order a proper nitrile washer, I cut a makeshift washer from a spare piece of SAI rubber tubing. A bit ghetto I know, lets see how long it lasts.
I hope I'm not doing more harm than good with these makeshift seals, if all I do is help trap moisture in there that might be worse than doing nothing?
Apologies for blurry picture.
