Double Hung Windows Tilt in

Good Afternoon,
We are looking to replace the window pivot blocks and constant force springs on both sides of the window. The Window weighs 24 lbs. for that pane.
The springs are 1/2 inch deep, and 1 1/8 inches wide. There are two springs per side, and they have j hook ends. They are stamped with CL and C.
The plastic carriers are 1/2 inch deep, 1 inch wide, 3.5 inches long and have two screw holes in each one.
It is a Kensington Window product: 3510/4510 Vinyl Double Hung
32.5 inches wide, 59 inches tall.
Thanks Jon