Upper mirror slider - contractor mirror wardrobe fitting

Seeking slider replacement for top track. Track width is 1 7/8" wide. Existing pad is rivetted to holder that slips into vertical support. Vertical support is 7/8" x 7/8" square folded metal. Existing pad is 1 1/2" wide by 1 7/8" long. Like to have adjustable replacement with smoother action if possible.