When I took my 11B apart 30 years ago, there were the remnants of plastic sheet on the inner parts of the door frames, so it must be original. One thing I’ve done is use a self-stick weatherstrip, a half round item and installed it on the front and rear of the door posts. Everything helps. On the tacking strip around the doors I’ve used Monel staples to hold the windlace in place and so far, no rust stains since 1985.
Anonymous