Originally posted by johnha (as jatrax mentions - although I don't agree Pentax changed the specs as all previous Pentax lenses weren't affected)
All I meant was that they added the powerzoom contacts, thus changing something in the camera, the change did not affect any Pentax lens. Whether they did it deliberately to cause issues with third party lenses, never bothered to check about third party lenses, or had to build it that way and thus inadvertently messed up third party lenses is unknown.
Had Vivitar and others followed the specification (or copied exactly the Pentax flange if there was no spec) there would have been no issue. Today, I would assume that Pentax would cooperate closely with third parties making lenses for k-mount especially in providing them with exact specifications and tolerances. I am not sure that was done as much back then.