24 year old powermaster. The o-rings inside it tend to breakdown and then the brakes no longer work.
Worse is how it works "every once and a while" tricking one into thinking "well that was wierd, all seems ok now".....then you get up close and personal with your garage door or a neighbors fruitless mulbery tree.
There is a rebuild kit for the powermaster, or you can take it out and put it away and install vacuum brakes.
Almost everyone here has a story about when the powermaster let go. I made it 3/4 of the way into the yard of the house at the end of my street. Similar to the other three TR's I have had.