The problem I have is the main unit wobbles about on the base, the rings are at the top of the base that fits into the main unit.
I have taken it apart tonight & I can see it's a new base that I need & not the rings as there are or was in my case two little pins that the rings go around have snapped off.
The base costs $7 so still cheap.
The track IR works fine, it just takes a while to line it up so it does not drop to one side as it can no longer support it's own weight.
Just bugs me that it's broken, so it's no big deal if there is no UK parts supplier.