A handy person from rhode island. says:
September 26, 2014
Trying to repair a couple ancient Nuprime windows in my father's old house, where the channel pieces have decomposed. The channel itself is a 1/2" w aluminum channel which is stamped "3030). The top sash guide (now broken) is stamped "3031". Having trolled your website, I believe that the Top sash guide is probably your product code 18-110. Based on the picture and my measurements of what is left of the channel balance top guide, a think it is probably your product code 19-002. Am I on the right track? If so, what other pieces might I need to completely replace the deteriorated plastic pieces for this side of the window (ie., rivet, etc.)
Paul from SWISCO responded:
September 29, 2014
Yes, Nuprime has used our 18-110 in the past. I think that's a good route to take. As for the balance, it's hard to tell without seeing what the nylon guides look like. You say they're badly deteriorated though, so pictures may not help. I would start by looking at our S390-31 channel balance. The good thing about this is that the shoe is a little bigger, so if that's what you need then it's perfect, but if you need the smaller size instead you can always shave a little bit off.