In 1979 I worked at a Kerr McGee station. My boss bought 2 of these,(which I now own both of) new. As far as I can remember we never did have those rings in them. One of the two of them has now been parted out to keep the other running. I have had to work the pump over two or three times now. It no longer has the ability to pump on low flame because the groove that they run in wore out and I "stroked" it and made it pump about 1/8 inch longer stroke than it did on high flame.
Yes, mine came with the diffuser ring. It is made of cast iron, but there is a guy on eBay selling some cut out of steel. Kutrieb part number is 910-001-1. Do you run yours without the ring?
Smells only when first igniting the unit as one has the cover off to get a wadded newspaper lit. After that I have never noticed a smell unless I drip some oil on the cover when hot during a refill. Mine pulls a good draft, so if you are experiencing an odor, you may not be pulling a strong enough draft through the flue.
