Here's some pictures of my flower nut fix. I had a problem with my flower nut assembly on my new Zoom/PK80 straight from the box in that the threads on the flower nut were so badly cut that the flower nut simply popped off when the clutch was engaged. For a full view of my problem see topic:
I had several fix options and suggestions such as welding the flower nut hole shut and retapping to fit the flower nut shaft, etc, etc. Also I could order a new flower nut and shaft but then I'd have to disassmble my new engine completely to install the parts. So here's what I did.
All I needed for this was a steel washer, a 6mm nut and a piece of sheet metal. First I redid the threads on the flower nut shaft with a M6x1.0 die for the M6 nut. By pulling on the clutch lever as to disengage the clutch enough of the shaft protruded to give good access for the die to re-do the threads. Then with a small ball peen hammer I hammered the washer into a cup shape to give it the recess for the nut to sit in. Don't make the cup too deep or it will bottom out when the clutch is engaged and the pressure plate won't engage with enough force and the clutch will slip or worse, be totally ineffective. I checked my clearances with some plasticene and left enough room as well to allow for clutch wear. Then I filed the edges of the nut on one side to make sure the nut sits well in the cup and engages on all the threads. Finally I made a little bracket with HVAC sheet metal to prevent the nut from backing off the threads and secured it with the standard set screw. Anyways, here's the results.
A little crude? Sure, but it should work just fine. Best of all this fix cost me under $1 in parts and a little bit of my time.