Originally posted by HarisF1 Sounds like a physical issue with the dial (resistance felt). Have you tried with other lenses to see if that might be an issue regarding the modes?
Yes, tried several other lenses - there's a mechanical failure in the dial mechanism and I think it might be related to the locking switch.
---------- Post added 10-22-18 at 11:30 AM ----------
Originally posted by redpit If you haven't dropped your K-1mkII (easy to check at the service)
I've never dropped the camera. It was working the day before when I used both D FA 100mm macro and Pentax A 50mm macro, so was switching between Av and M with no issues at all. Overnight it was securely placed in the middle of a low table, and unless some sprightly fairies threw it around at night then placed it carefully back in the same position, it hasn't fallen off... The following morning, it simply didn't work. I was shooting in a forest, dry warm conditions, using a tripod so it didn't even have a chance to get dirt on it. Whatever happened must have happened when I turned the dial that morning, and must have happened on first touch. I guess from the sound of it it's not exactly the same as the K1 issue, since I can access the modes still (after much fiddling it will now go into the missing modes, but the resistance is almost enough to make the dial un-turnable). I'm sending it in this week, hopefully they will give a report on repair.