I tried a couple of things. I found that most self adhesive closed
cell foams were to stiff and not compliant enough to make a good seal
with the low forces applied to close the various flaps. Open cell
foam was better, I think it was a weather stripping white foam I
used. On another flap I tried polyester woven batting type material,
thin, in sheets, a strip glued on. Its still in good shape, I have
the heater box in the workshop after removing from my '82.

alistair