Cool! Mind having been blown confirmed!
Maybe you can find Happy Days on Blu-ray and see if you can discern any identifying marks.
Although, seeing as how Mr. Winkler is still very much alive and still acting (new season of Barry just started!), their use of the term "estate" raises even more questions. If it was his, he probably just got tired of it taking up room in his garage, not working with no key. (If it was a jukebox, he could have just given it a whack!)
Still can't believe the thing sits for 5 years, and I happen to look at the Pinside Front Page, which I only do occasionally when I'm bored and caught up with all the threads I follow, less than a half hour after your post about buying it! Not earth-shattering or anything, but very odd!
Oh, and congrats! Of course, to the right person that could be worth a lot more than the going rate, that is if you can confirm it was the very game on the set!