I have a couple of windows with 1/2" non-tilt channel balances that have failed. I've identified the replacement as your Series 390 balances with the 19-001 top and 15-001 shoe. One balance is stamped "1930 BSI" which seems obvious enough--it's 20" long so I will order the 1930 option.
The other balance is stamped "3190 BSI 32" which doesn't seem to fit in your option list. The channel is 32" long, the vinyl sash it's supporting is 41" x 31" (glass size, or DLO). What would your recommend for the strength of this balance?
