New Style Quick Tilt Single Coil Spring Constant Force Balance  uses a different pivot bar than the old style. If  changing an old style, you will need to change Pivot bar also, old style had a T-Head, new style uses round head pivot bar.

Number of Coil Springs: 1 - Single Coil
Weight: 3-10* (Number stamped on plastic cover)
Number on Coil: None
Handing: Reversible (see 4th image -- cover pops off and coil direction can be switched)
Carrier Width: 1-1/4 inch (1-17/64 actual )

*Size 10 has been discontinued by the manufacturer. Replace with 534309 (select size 10). This is a tandem coil balance built to hold the same weight. You can replace your single coil with this tandem coil. 

Carrier Thickness: .540 inch (35/64)*
Overall Length: 3-3/8 inch
Sold: Each, Priced Each - Best if replaced in pairs

Sold as Complete Unit, no individual parts available

NOTE: The Plastic Carrier was available in 2 thickness, .540 (13.716mm) and .600 (15.24mm) * It Appears the .540 can replace Quilt Tilt double coil spring balances that are .600 inches thick