Earlier, "Phil Jeffery" wrote:
I had a similar problem a while ago when the sliding
portion no longer had the same curve as the canopy
causing a slight gap.

I've also had a similar problem, fixed with a similar solution. My
window was twisted out of profile; it touched along the front and top
edges, and stood proud at the bottom rear corner. I used a heat gun to
carefully heat the window into its plastic range, and then torqued it
back to shape.

Oh, I practiced on an acrylic scrap before attacking the window
proper. That helped.

Bob K.
http://www.hpaircraft.com/hp-24