[Rick Norwood]

I have seen these boosters fill up with brake fluid that leaks out of the master cylinder due to a bad seal. Have you had to add brake fluid? You might be able to remove the vacuum line and look into the booster or carefully insert something like a pipe cleaner into the hole to see if there is brake fluid in the booster. Just be very careful not to rupture the diaphram inside the booster.

Hope this helps.