Continued work on the Airmaster SB-18.

Ready for the changing of the o-ring.

Slipping on the new o-ring with a spatula.  Went on easily.

You can see the new one is thicker and it's a smaller diameter.

Re-installing the blades after I regreased the hub and blades

After tightening the retention nuts down (15nm) I measure about a 2mm gap, which seems bigger than before.  I've emailed Airmaster to confirm that this is OK before I tighten down the screws.