Oh good (on the window pics). I now know for sure that mine are straight in the vertical dimension (i.e. the verticals on each side of the window) because I had occasion to check them. I had the window out when I was tabbing in the closet, and I didn't think to clamp that area straight, and so the closet wall induced a slight wee curve there. At that point I was almost hoping my
windows were curved! But no such luck. Straight as a die. So I had to cut out that bit of tabbing and then I clamped two boards onto that section to keep it straight while I re-tabbed it.
But back to the Bargman L400.....