Exactly. I see pipes listed as "no low bidders" in the description, but I think you have no recourse in a BIN. If you canceled the sale, that would look bad on your ebay history if done with enough frequency.
Put it in the freezer for several hours, then CAREFULLY, try twisting to remove the stem. The tenon of course will be near frozen, so don't snap it! An alcohol soaked cleaner inserted can also loosen build-up.
I've never heard of anyone in Houston.
Lone Star is in Texas, I'm not sure if he makes stems.
https://www.facebook.com/lonestarbriarworks
Ryan Alden is also in Texas, but I'm not sure he makes stems either.
I've never heard of or seen a Dunhill system pipe with a 2nd chamber like Peterson.
Filter pipes, like George shared and 60's or so had the metal tube, that went into a tapered tenon.
Mike Glukler told us that upper case K's began in 1969 and went to lower case k's in 1982. So, I suspect that is your date range.
I have a 2k size Sea Rock 65, but the rustication is now where near that gnarly!