Hi Geoff,
For many years now the BOSS team (Backyard Observatory Supernova Search) has successfully searched and blinked images using the powerful Seghal Supernova Search Tool in Maxim DL. It's included in one of Maxim DLs lower cost versions but still not cheap.
Also here is a link that maybe useful.
https://www.theastrogazer.com/home/image-blinking
Just found a blinking programme called GrepNova - I have never used it but it seems it is free and the link to the download can be found on this site. If you use it let me know how it works for you!
https://in-the-sky.org/software.php
Best,
Peter