Marvin double hung balance replacement

A quick learner from Montana says:

Hello,

I have several windows that won't stay where I open them to. They can free fall. They are approximately 20 years old and have a blue plastic part (I think it is the clutch???) that is broken or the string going to them has broken.

I see that marvin uses a new system. Is it possible to upgrade?

Thank you

User submitted a photo of a window balance.
Profile picture of Paul
Paul from SWISCO responded:

I believe that the clutch you're talking about is our 15-014 lock shoe. The balance this is most commonly used in is our Series 751 tilt ribbed balance. Is this correct? I can't confirm based on your picture. Carefully compare these to your own hardware to confirm. For instructions on how to replace these, see the video below.

Based on your old balance's appearance, I believe you need a replacement balance with a length of 37", and therefore our S751-37; but measure the length of the metal channel to confirm this. You will also need to select a stamp option, which designates the spring calibration of the balance. Your old balance's stamp is from a different rating system, but not to worry. To know what stamp to select, obtain the exact weight of your window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option we offer on the S751-37 product page. 

How to install a ribbed tilt channel balance with knife lock shoe
How to install a ribbed tilt channel balance with knife lock shoe
VIDEO
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Classifying Channel Balance Fittings
Classifying Channel Balance Fittings
GUIDE
READ >
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