I have a tiny weep coming from the divertor valve, It fills a teacup twice a week and is easily collected but slowly getting worse. Removing and stripping down the valve, everything appears to be in order but still this tiny leak. The boiler's only a few years old and is operating normally.
it's probably leaking where the rod passes out of the valve to activate the microswitch. you'll need a new end seal or one of the tiny o-rings from a gionnoni service kit.