I would call them (contact info is on the website PaperPrincess posted) and explain the situation. They sell parts for the carriage:
http://www.newjoyquilting.com/cart/s...nd+Accessories but perhaps they can also sell you the carriage itself.
Here is an eBay site that provides information about a quilting frame carriage that may be useful for your dh; however, the sizing of any carriage will be specific to the frame.
http://www.ebay.com/itm/Machine-Quil...oAAOSwQiRUqz-Y