So has anyone had much joy rebuilding these?
My rear brake has always been problematic, I’ve gravity bled it, ive even done this vertical.
The front brake works a treat but the back has always lacked power, im not sure if something inside blown, can you rebuild these like you can with Avids?

No small parts available so most people don’t bother, since if you find a problem you can’t get the parts to rectify. Of you had a friendly industrial seal supplier and a bit of time you might be able to sort something – I’ve successfully done this for a fork in the past, but factoring time and hassle it’s probably easier to pay the money for a new lever body.

Hi Scienceofficer thanks for the reply. Thats the conclusion i was comming to. I had a good look about it, decided to order another so hopefuly its here monday, then i may as well butcher the old one to see what gubbings are in it and what failed.
I always assumed it was down to poor bleed but it would never sort it out, time just to get rid. Not very great on shimanos part though, good for their proffit mind. I had thought with all the bleeding problems people had and lever travel then i was to blame but lever feels good so it must be seal in the caliper

had 1 full set of zees on my big bike, replaced with saint levers as snapped back one in a crash and on my second rear xt on the trail bike as the first leaked. always had problems with the rears and never the fronts, bled all of them countless times to no avail leaving them mushy or going straight to the bar when i really needed them not to but learnt a few tricks on how to get them better……
the rear suffers from a lack of power if the pads get below 50% so change often and save the old pads for the front, SS pads are a bit fatter than most so work better for longer, they will fit just push pistons right back
use a syringe (should screw into the ‘ bleed port’ on the lever without leaking) to force fluid in to the lever reservoir leaving the caliper bleed port tight as this should push the pistons closer to the disc, fluid may leak from the seals around the base of the lever, if it does get rid.
i also use pentosin lhm fluid (£10 for 1 ltr) as its a bit thinner, a hell of a lot cheaper and it seems to give better bite.

Ive also had a caliper separate spewing fluid all over the pads and disc as the t25 bolt that holds it together worked its way loose, cant even use lock tight on it for fear of contaminating the brake fluid.

brill brakes but had to many problems with them to buy again,,,, back to hopes next time.