in your june 10 posting you said "don't see any bushing" there should be a rubber bushing (dust cover) or rubber guide to keep the actuating rod straight and in line, otherwise it could move around a bit, if it moves around, it may not return all the way, and not totally release the pressure in the brake system.
i understand how frustrating this is, i went through it!!
a great source to understand how the master cylinder works is http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html
i tried to attach a photo of the rubber bushing on the push rod but the file size was too big, i don't know how to get around that problem.
as an aside, any chance that there maybe a vacuum leak on the booster, any sucking noise from any of the vacuum hoses???
nazgul
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