These are single spring balances, both have broken springs.

A quick learner from S. Yarmouth, Ma says:
August 7, 2018
The sash weight is 12 lbs
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Paul from SWISCO responded:
August 13, 2018

For single spring balances supporting a 12 pound sash, I recommend our S190-6 coil springs, one on each side.
Coil Balance Shoe
Coil Balance Shoe
15-180
$3.97
Double Support Detent Clip
Double Support Detent Clip
15-181
$6.17
Balance Bushing
Balance Bushing
15-182
$1.80
640 S190 Coil Balance Spring
640 S190 Coil Balance Spring
S190-640
$9.74
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