Hi Gary, I've been able to narrow my suppliers to just a few.
Universal Sewing Supply in St. Louis is one of the best sources in the nation for industrial machines. www.universalsewing.com
They are phenomenal when it comes to things like needles and machine parts. Get their catalog, it's great. Don't lend their catalog out, you'll not get it back.
For UV resistant thread and parts, I mostly use Challenge Sailcloth from Vernon, Conn. 1-800-962-4499. Get their catalog also. They have all the good stuff for sail and awning making including all the good grommets etc.
The guys on the upholstry website I provided earlier can help you with upholstry supplies.