stamp on channel balance

Question

We are attempting to replace the channel balances on several windows which were in our home when we bought it in 1978.  The stamp on the channel from one of the windows says "2420".  This number is not included in your chart.  What would be an appropriate replacement?  Thank you.

Tom · Accepted Answer

We have dozens of different balances with that stamp. It's not a product code or anything, it just indicates the strength of the spring.

In order to figure out what Series this is, I need you to remove an undamaged version of this balance from the window and show me clear pictures of the top and bottom nylon fittings. I will also need to know the dimensions of these fittings. The video below will go into more detail.