This isn't much evidence, but it's at the general location that is commonly known (by the Burbank Airport) and Jay is supposed to have more than one building, one for working on the collection, at least one for storing them, and the sign above the door says "Service entrance"
And the amount of rubber on this side street in front of that gate, well... draw your own conclusion... but the people I asked while taking this photo said Jay is always on these streets. Soooo, I'm figuring I've found it. Not like that is going to do anything for me, but it's neat
