Hi Glyn,
In my '73, the arm holes are in the screen frame. There is supposed to
be something to keep the bugs from coming in those slots. Mine has and
had the "bug fuzzie " strips, two strips of stiff grey fringe that are
glued on the back side of the screen. They part to let the arm go
through and keep the bigs out of the rest of it. There is also a clear
sliding 2 layer plastic thingy that will do the same thing.
Dunno what a '69 would have, but keeping the bugs out is a good idea....
Daisy