Replacing the plastic clips with metal brackets and getting new regulator does not solve the original problem: split rubber channel with extra space! We need to ether replace the rubber guides (are they still available?) or build up some material for TIGHTER window fit (front to back).
She's replaced both the regulator and the rubber weather strip with new components & is still having tilting issues.
For some reason one of the plastic guides is not properly engaging the vertical track.