I don't seem to be losing much fluid. I have a very small leak at one of the connections, but not much. After I go over the system, I will have a good firm pedal, but it will gradually go away. I didn't rebuild the booster myself, but I did buy a new one from NAPA. I feel sure it was rebuilt, because I don't imagine anyone is making new ones any longer. As I said earlier, I don't think the booster is working, because I can't hear it doing anything, and while it doesn't take a lot of pressure to work the brakes when they are up, it does seem to me they should be a little lighter if the booster was doing its job.
I have never taken one of these apart, but I don't imagine it is too complicated. Have you had any experience rebuilding one? I don't remember seeing a plug on the booster, but will look for one, the next time I am under the truck. Thanks Allen