Primary mirror stabilization
To prevent 'mirror-flop' I decided to take the primary mirror assembly apart and epoxy the primary in place. After carefully focussing the scope at infinity, I marked the position and started the disassembly. Here you can see the two cylinders that define the sliding motion of the primary. The inner cylinder was fixed to the backplate of the scope, and the mirror was tied to a cylindrical sleeve that slid over the center cylinder.
Here you can see the collar on the rear of the primary and the threaded bolt that connects to the focus knob.
Here I slathered epoxy on the cleaned inner cylinder in preparation for sliding the primary down to its final resting place.
After the epoxy set, I reassembled the entire optical tube and verified focus (whew!).