Help identifying window spring balance

This is a very old Caradco wood window. We might be able to supply this, but they're difficult to get a hold of these days. Before we can go further, we require more information.

First, it appears that the tube length is 19-1/2" long. Can you verify? Make sure that you don't include the top and bottom fittings in this measurement, we ONLY need the tube.

Additionally, i need you to pull the nylon top fitting out a little. This end of the spring should have color painted on it, and I need you to tell me what the color is. 

Lastly, please give us the size of the visible glass, width" x height".

Great, thank you! Please give us a little more time to look into this and we'll get back to you as soon as we can.

I'm very sorry to return to you with bad news. I just received word this morning that this balance is finally discontinued and no longer available for us to supply.

I feel really bad for getting your hopes up, I truly thought we could still supply these. We tried to sell this balance for as long as we could, but it seems the well has at long last run dry.

I'm not sure who may still have these, they were already difficult to get ahold of even when we could. My recommendation is to contact a local professional who is familiar with homes in your area and see if they have a source. Odds are your neighbors use the same kind of windows, and if that's the case then a local professional may know where to get them.