Not sure how these work

A home owner from Swansea, Mass says:
July 18, 2020
I have 4 windows that have this style regulator. The white item with 2 screws is new to me. There are letters from A-F on the sides and the #2. All the other windows have spiral type. I am not familiar with what I have. Do you recognize this style. I'm afraid to unscrew the part, in case it's under tension. Looks like I'll need some pivot lock shoes as well.
Thumbnail of the uploaded file named IMG_3890.JPG
Thumbnail of the uploaded file named IMG_3888.JPG
Thumbnail of the uploaded file named IMG_3889.JPG
Thumbnail of the uploaded file named IMG_3891.JPG
Profile picture of Bob
Bob from SWISCO responded:
July 21, 2020

This Pivot Shoe looks like our 15-175, which uses our Series 152 Coil Springs. Those springs are what are inside that housing support in your photos. If the support itself is undamaged, you could reuse it; otherwise, we use a different support system with these springs: the 15-143 Bushing, the 15-144 Bushing Cap, and the 15-145 Support Barrel sandwich around each spring in question. The video below shows how to replace multi-spring balance systems. While a different Series, the principles are the same. 
Coil Bushing
Coil Bushing
15-143
$0.97
Coil Bushing Cap
Coil Bushing Cap
15-144
$0.70
Coil Support Barrel
Coil Support Barrel
15-145
$0.49
How to Replace a Triple Coil Balance System
How to Replace a Triple Coil Balance System
VIDEO
WATCH >
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 3-4 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.