I know this is an old thread, but these kits fall apart if you don't put a tiny dab of epoxy (or thick CA glue) inside the screw-in button at final assembly.
I'm having to do warranty work (read buy new kits for the parts) now on units that "disassembled" with very little use by owners who didn't know they could fall apart so easily. Grrrr. These were Christmas presents, so I feel obliged.