Channel Balance - 2840-Q

I have a Channel Balance w/block & tackle w/spring. Stamped 2840-Q no manufacturer on part, window or glass. Channel is 9/16" sq.(outside) by 29" long and has hook on end that attaches to pivot(tilt window). Windows are about 20 yrs. old. Do you have a replacement? I have purchased from you in the past.

The block and tackle is slightly different, but I do not think that would matter. The shoe(hook) is one solid piece of flat metal with a hole for the cord and a hooked arrow shaped point. Also, the channel is pre-loaded with a tension, since the sash is heavy.