Fixing it is actually pretty easy. The handle is a hollow tube with the brushes connected at the end on a square block. The block slides up and down the pot housing. The back plate of the pot housing has a very small rod attached to it that goes inside of the hollow tube, with the spring between the rod and the tube.
When I broke mine, I cut off the rod (the spring was lost in the tube’s ejection) and replaced the cavity left in the tube with a solid piece of spring steel rod (landing gear wire from a retired RC plane). The spring now goes on the outside.
Biggest issue I have is the two small flat head screws on the bottom of the pot. I can’t get to them while it is on the board so I have to de-solder the pot to get the back off.