Here is how I fixed my one armed Mr. Hankey:
Find a piece of heavy gauge electrical wire (Solid or stranded house wiring- about #12 gauge) to use for the arm. If you can find black you don't have to paint it. Get some epoxy putty and use it to make a hand on the end of the piece of wire. When it's hard you can carve it with a Dremel or some small files. Take a drill (drill bit same diameter as your wire) and carefully drill about 3/16" into the Mr Hankey body where the old arm broke off. Cut your new arm to length (a little extra for the length that will go in the hole you drilled in the body). Put some glue in the hole and press in your new arm/hand. Touch up the paint and paint the hand. The new arm will bend, so it will never break.

Don C.