I know of this brand of cabinets, but have never had to fix the supports. If faced with this, I'd probably improvise a solution with something I could find. Lowe's carries quite a few cabinet glide hardware replacement parts.
Also try Bainbridge: www.BainbridgeMfg.com
237 W. 3rd Street • P.O. Box 487 • Waterville, WA 98858
(509) 745-9555 • 1-800-255-4702 • Fax (509) 745-9666 • www.BainbridgeMfg.com