How do you fasten the wind-lace to this retainer strip. The groove is about 1/4" x 1/4".

I think you could clean the crease and lay in thin bead of glue (like model cement ) then push in the fabric with a small knife blade. blue38

On my '40 the windlace was held in the bracket with paper cord inserted into the fold of the windlace. I followed the same procedure when I installed the new windlace. Double the material and insert the cord (I used chalk line instead of paper cord)by using a dull blade screwdriver to tamp the cord and material to the bottom of the bracket crease. My retainer strips are slightly wider at the bottom of the crease.