Balance assembly part identification for MI window series 380 DH

Purchased custom double hung Windows from MI windows in 2008 but they are now discontinued. The balance system is broken on several of the Windows, so when you unlatch the bottom window to open, the top window comes sliding down, there is nothing holding it up. I have attached a pic of the broken balance (which is approximately 4"), along with the pivot bar and the piece that attaches between the two. I could not find any part numbers. Any help that you can provide would be much appreciated.