This worked OK, but I have a request for an enhancement.
It would be an improvement if Scrivener told me when it had finished the find and replace.
I was working on a file with 60,000 words, and Scrivener sat there as if it had gone on vacation. 
Sorry about that. Scrivener for Windows is a work in progress and finding little ‘anomalies’ like this is exactly what we’re out to do. Thanks! I’m sure it’s on Lee’s To Do list…