Odd manual focus problem - DA* 60-250 + 1.4x DA HD Teleconverter

This is a newly developed fault which I don't remember seeing until this weekend.

Essentially, if I try to manual focus while the lens is connected to the teleconverter, I can go from infinity to close smooth as butter. However if I try to go the other way, the ring "catches" a lot and doesn't always adjust focus. Sometimes it locks up altogether.

This happens whether the pair is connected to the camera (K-5 in my case) or not. However if I disconnect the lens from the teleconverter, the problem totally goes away. The only thing that I have done recently that may have any bearing is to put the 60-250 and teleconverter onto my K-10D. I realise in hindsight the K-10D has no support for this converter, but I can't see how that would have affected things.

Odd, right?

Solved.

Thinking it through, I realised the only mechanical link between the two parts that could affect focusing was the screwdrive. So I checked the screwdrive on the teleconverter, rotated it and pushed it in a couple of times. It "clicked" then everything went back to normal.