The bushings are not meant to stay in the tube. They are only there to keep the grill brick centered until the epoxy sets on the aluminum piece with the 2 set screws. I installed the displacer piston top and rod into the machine. Placed the bushings in the cylinder, put some epoxy on the displacer grill brick and pushed it into place on the machine. The next day, I removed the whole assembly, took out the bushings and reassembled the completed displacer piston and was very pleased that it seemed to maintain the 0.065 space between the piston and the cylinder wall. So today, I'm painting the displacer piston with high heat paint. And wouldn't you know it, it falls out of the unit that was holding it during painting and managed to break. At least the break was clean (2 pieces) with no visible flakes. So I just epoxied the 2 parts back together and will see tomorrow if I succeeded. If so, I will put it all together, add some heat and see if I have a working machine or a paperweight. Also, thanks for all your help.
Grasshopper
Grasshopper