Originally posted by henniker I'll stick with the workaround!
Today I was considering buying the Sigma nearest equivalent- 10-20mm. I felt brave enought to remove 6 tiny crosspoint screws from the rear of the Pentax 12-24mm lens. Don't try this!
Tiny gold electrical contacts and springs sprang out and one landed on the carpet. A tiny curved polythene spacer came out too. The rear black plastic cover had fractured round the minute grub screws holding it on.
With careful perseverance I managed to reassemble the contacts and screw down the rear silver metal ring. I tested the lens in the K7 and it worked as before. The zoom ring still sticks until I change to a closer focal length.
I've ordered the Sigma 10-20mm lens and once I get it I'll send the Pentax one for repair. It was too expensive to not have it working properly.