He's on this forum and others as LeeMajors but that's linked to his email anyway. I figure his business email is the best way and that he's probably busy with something or other; he's a one-man show after all. Keep at it I guess.
EDIT: Your email could have also ended up in his spam folder as well, like mine were. Try messaging him from a different email account that you know isn't compromised.
I suppose if you really want to get his attention, you can do what I did and contact your credit card company and order a charge back for not getting the products you ordered and not being able to contact the seller to resolve the issue. It would be the truth after all and what else could you do? He'll notice the charge backs on his accounts and come screaming at you, and you could point to the list of emails you sent out a long time ago trying to get his attention. Wait 'till about a month before you have to resort to this.
Keep us in the loop over what happens, I'm sure he'll get back to you. If not, you can probably sell or keep those adapters and by then I can have a 3D printed 1913 adapter ready for you.