Broken Ring on filter

Hi, there.
I haven't posted much on here but I'm hoping someone can help. I apologize that I don't know the exact terms to describe my issue. I have a Hayward sand filter. While turning the handle on the filter to change from one setting to the other, like from filter to backwash, a ring that was under this handle broke. My husband took it to the pool store and got a replacement and attempted to replace it but it didn't go so well. He got the ring in but it's not in properly. Now the filter settings are misaligned. To filter the pool the handle is actually set on Waste. He said he tried for hours to fix the issue with no success.

Any one have any suggestions on how to fix this issue? Thanks in advance.