Broken plastic part for spiral balance

A home owner says:
April 22, 2012
We have vinyl double hung, tilting windows. When I disengage the lock, the top window drops down. We have found small plastic pieces that have obviously broken off, looks as though they are from the bottom of the balancer. If so, would this cause the top window to drop open?

I have not been able to find out who the manufacturer is, however, there is a label on the window which reads as follows:

31 3/4 x 53 1/4
(85WS31653266MHLD)
North Brunswick Stock

Any advise you can offer, will be much appreciated - thank you.
A user submitted image of window parts
Profile picture of Paul
Paul from SWISCO responded:
May 15, 2012
Thanks for posting! A broken tilt shoe can cause top sash to fall, but if shoe is intact then you might have to simply charge the spiral balance. For tools on how to charge, please see our 75-006. If that doesn't work, then you may need to replace your hardware.

Looks like you might have our Series 600 spiral balance. Furthermore, the broken tilt shoe looks like our 15-046. Do you think these may work for you? Take a look at them and compare them to your own hardware.

You may also want to check out our video on tilt windows, which shows how to replace a spiral balance, as well as how to charge one:
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