I recently bled my guide brakes after they got spongy, this after 18 months, plenty of air and some pretty dirty oil removed from the system no problem. Brakes then worked great for a few rides but now the back has rapidly deterioted. I’m guessing it’s obvious that I’m getting air into the system.

Can anyone point me in the direction of the best/easiest areas to check. I’m not seeing any signs of oil leaking out.

Any help appreciated.

If they do the same as elixirs the internal seals deteriorate but replacing them is relatively simple and makes them good-as-new.

That said, when it happened to my elixirs there was no temporary improvement. You did use dot fluid, right….?

that link has a link to the parts list – might have to contact Fishers to get a rebuild kit.

Thanks for the link Jimmy.
I did use Dot.