Shimano BR-M355 rear caliper.
I've very quickly managed to contaminate three sets of brake pads through fluid leaking (I think) from the bleed nipple. I've twice taken advice from local bike shop who inspected the caliper and assured me nothing was wrong, advice was to buy more premium end sintered pads. Fair enough I thought, give it a try. Few weeks later and back to square one - no braking power and very noisy.
The dust cap is missing from the bleed nipple, but I assumed this was one way and wouldn't cause it to leak?
Essentially, the question is can I fix it by replacing the dust cap, top up fluid and replace pads, or is it a case of replacing the caliper and starting again?
Any advice gratefully received. Thanks