On Sat, 2 Nov 2019 18:31:47 -0700 (PDT)
wrote:

The ball-tops don't screw on. They are molded onto the rods.

Darren Harris
Staten Island, New York.

Have you looked through the different handles and shafts at McMaster?

https://www.mcmaster.com/control-handles

On the top left side of the link page you'll see a picture of a ball-top
shafted handle (Handle Style - Machine). Click on that and scroll down
the page. Maybe your could just buy the 3/8 inch ball top handle in 4
inch length and cut it to suit. Providing of course the bottom part of
it can be made to fit

--
Leon Fisk
Grand Rapids MI