Replacement parts for window

Balances are working fine. However, the plastic part that connects the balance to the window guide has failed. The diameter of the failed portion of this part (the portion that makes contact with the guide) is 1/2". This part slides in a channel 1 3/16" (30 MM) wide and 1/2" deep. The balance tube is 22" long. I forgot to get the tube diameter and, if needed, it will have to wait since the house is in Canada and I won't be returning until December. I couldn't find any manufacturer information anywhere on the windows except for the glass (IGMAC #029410 A.W.I. PARADISE 1995). I want to replace this plastic part on four double-hung windows (they are all failing). Are these parts available separately? If not, what are my options? Hope this is enough information. Thanks for your help. Larry