It’s now almost a month later, and finally I managed to get ScamZapper reinstalled last week. I have no clue why it worked this time and not on the various previous occasions I tried it during the last few weeks. What ultimately worked was loading the ScamZapper app (installed in Apps), that’s there to help out with scams not yet covered by the browser extension. Like the regular updaters, it too checks for an installed extension and offers to install it if none is found. This time that did work (previous trials didn’t), albeit that app v1.4 installed extension 1.3.6. There may be an issue with the installer script, but I have been too lazy to scrutinize that after a first glance didn’t show anything obvious.
Interestingly, a few days after the successful reinstall, I ran into exactly the problem ScamZapper is supposed to handle on an otherwise normally behaving Wallpaper site. Somehow I doubt the updater that wouldn’t install (1.4 vs. 1.3.6) provides the signature for this problem site, but in any case, dealing with new problem sites is what the ScamZapper App is supposed to be for. I’ll upload the requisite data to have this particular one added.