single-handle Aqualine shower handle

Single handle Aqualine Shower Handle. The one we have (which is broken) is plastic with a metal collar w/set screw. Looks like the shaft it fits on is 3/16 w/flat spot for set screw. Plastic under collar is broken.
: Anyone know where I can find manufacturer or replacement handle.

I believe Aqualine was the Sears Brand for Valley. Handles for Valley are available. Search on line, of visit a plumbing store and compare the Valley parts to yours.