I think I got it back to where I want it. When I upgraded I checked the rollback option and it proved useful. I had to retype the serial number and reauthorize, but it used the same authorization file from when I first loaded Kontakt.
Does anyone else have problems with very slow launching of Kontakt 1.53 and similarly slow loading of multis? By comparison, K 1.5 launches instantaneously and my multis load much faster.
If this is an old issue I apologize for the distraction.