A professional from Blacksburg VA says:
December 14, 2015
Hello my name is Dale Ferguson. I am a maintenance supervisor at CHP in Blacksburg VA. I have several windows with these constant tension balances but am unable to locate replacement parts. I have found that when I raise the window the tilt locks installed hit these balances and one or the other breaks. The balances have 2 coil. I sent 2 pictures. The tilt locks may have been replaced with incorrect ones for this system at some point. I would greatly appreciate any help you can offer in this area. I will need to know if these balances or equivilent are available as well as the correct tilt locks for them.
Tom from SWISCO responded:
December 16, 2015
Looks like just the balance cover is broken. Assuming the balance coil springs work fine you can probably get away with just replacing the cover. Start by looking at our 15-204 dual coil support cover.
As for the tilt latches hitting the cover, it sounds more like an issue with the placement of the balances. Regardless of what tilt latches you have installed, they will still extend into the jamb track and hit the balance cover, so changing them to a different type will probably not solve the issue. On the other hand, if you install the balances too high, there's a chance the window won't be able to close fully.
If I were you, I would play around with the balance placement. Try raising the coils a few inches and see how far down you can bring the pivot shoe before you redrill any holes. That will be a good measure of whether the window can close or not with the adjusted height.