The sash inside cavity has a ribbed seal on both sides; ribbed seal is glued inside the frame. The friction between ribs and new glass is significant. Lubrication does not improve the ease of insertion of IGU. Vinyl frame sides are not separable. Any suggestions on easing the installation of IGU in the vinyl sash frame without cracking glass? Yes, we cracked one new pane. I am repairing
6 sashes. We are considering removing the glued ribbed seal on one side; then caulk between the glass pane and vinyl frame.