Bottom line is yes it is confirmed the registration page is broken. and I think I know why.
Try this yourself. Open up your browser (Chrome) in incognito mode
1. go to
http://vintagehondatwins.com and register
2. Fill out the month, day, and year and hit Proceed.
3. You will immediately get this
[h=2]vBulletin Message[/h]
You have left a required field blank.
Chrome's developer console shows
This browser is AJAX compatible
register.php?do=checkdate:85 Mixed Content: The page at 'https://www.vintagehondatwins.com/forums/register.php?do=checkdate' was loaded over HTTPS, but requested an insecure image 'http://vintagehondatwins.com/images/vht_header.jpg'. This content should also be served over HTTPS.
vbulletin-core.js?v=425:11 Firing System Init
vbulletin-core.js?v=425:11 Fire vB_XHTML_Ready
vbulletin-core.js?v=425:11 Fetch Cookie :: vbulletin_collapse (null)
So it looks like there is an image being referred to 'http://vintagehondatwins.com/images/vht_header.jpg' that cannot be accessed because it is non-secure (non SSL)