Window won't stay up, missing both channel balances

Hi Marilyn, thanks for writing in. Is this a non-tilt window, i.e. it can't be tilted inward for cleaning? Is there an identical or similar-sized window in the house with the balances intact? If so, can you remove one of those balances and show us pictures of the nylon fittings on both ends? See the videos on this page for assistance. Finally, for the window sash in question, we need the exact weight of the sash (this can be procured by placing the sash on a bathroom scale), as well as the height of visible glass in the sash. We'll do our best to narrow this down from there. 

Thanks for the photos, Marilyn. It looks like you might have the Series 380 Channel Balance. This balance has top and bottom fittings with wings, or side tabs, as yours does. The bottom shoe has a depth of 1". The depth can be thought of as the 'heel-to-toe' measurement of the bottom fitting. Please confirm your balance has that same shoe depth; let us know if it differs at all. 

To be clear, is the visible glass height 28"? If so, you should need a balance that is 1" longer, so see our S380-29. If the sash weighs exactly 28.6 pounds, use stamp option 2850, which will support a sash in the weight range of 28 through 32 pounds. Finally, for a Top Sash Guide see if the 18-180 has dimensions that match what you need.