Need new support coil balances for doouble hung vinyl tilt windows

A landlord from Waterford, Michigan says:
March 16, 2018
I have a rental home with two windows that won't stay open when opening. The city inspector said I need to repair or replace these windows to comply with the building codes. Only the bottom sash needs to be repaired. The first sash is 16.5" H X 31.5" W. I do not know how much it weighs. The second sash is 17" H X 44" W. I do not know how much it weighs. Please help, I do not want to have to replace these windows! The only markings I have found was an F stamped on the copper colored coils that were in the kitchen and a D stamped in the coil on the silver colored coils that were in the bedroom. Please help, thank you.
Coil assembly
Profile picture of Paul
Paul from SWISCO responded:
March 19, 2018

Thanks for the photos. Our 15-177 pivot shoe should be a match to your shoe. I also want to mention that our coil springs are screwed on to the pivot shoe with a 33-071 screw. Your coil springs should be compatible with our Series 152. The one spring you are showing us stamped with the letter, "D" will be our S152-4 and as for the spring stamped with the "F" will be our S152-6. If you like some more insight about coil springs, I have placed some media guides on this page you may find useful. 
#6 x 3/8 SS Pan Head Screw
#6 x 3/8 SS Pan Head Screw
33-071
$0.21
Coil Balance Shoe, Slate Blue
Coil Balance Shoe, Slate Blue
15-177
$3.47
4 lb Series 152 Coil Balance
4 lb Series 152 Coil Balance
S152-4
$4.70
6 lb Series 152 Coil Balance
6 lb Series 152 Coil Balance
S152-6
$4.80
How to remove window pivot shoes
How to remove window pivot shoes
VIDEO
WATCH >
Anatomy of a tilt window
Anatomy of a tilt window
VIDEO
WATCH >
How to Replace a Triple Coil Balance System
How to Replace a Triple Coil Balance System
VIDEO
WATCH >
Removing a Triple Coil Window Balance
Removing a Triple Coil Window Balance
GUIDE
READ >
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