Two items about XL focus rings:

I have created a Web page that shows closeups of damaged and healthy focus ring tabs. If you are thinking of buying an XL or just wondering if yours are OK, this page can be helpful.
http://www.staff.uiuc.edu/~b-wallen/BN_Photo/Graflex/XLLensMnt1.htm

On seeing some custom machined aluminum focus rings on eBay, I wrote to SKG to see if they had considered manufacturing focus ring replacements in quantity. They have, but do not have active plans to do this immediately. Expressions of interest by potential buyers might move this project along.