Are you refering to these bushings?
When they wear down they tend to pop off, i assume thats what you are experiencing.
Unfortunatly that bushing isnt sold separately, it comes with the rod,,,
The assembly is refered to as the wiper transmission linkage.
Might have trouble finding one tho,,,,if you want i can help ya to improvise it,,,just let me know.
If not, please click on accept.