Originally posted by Canada_Rockies I returned my 50-135 to Pentax when I sent in my k10d for repairs, and because it had "Moody Mood" syndrome and the warranty was running out. It was returned to me, and appears so far to be working much better. The notation was "Cleaned and adjusted contacts". I've been doing the cleaning bit quite often, but had no idea the contacts could be adjusted.
I just wish that Pentax or some technician would come out and say what the dang problem is. There was some statement over on DPR that there was a plastic bracket that wasn't installed correctly. I find that hard to believe when we see the statistics in this poll that show a number of failures on all lenses but 200 and 300. All these lenses couldn't have been manufactured at the same time. Very irritating that they wouldnt' come out and say what the problem is. Of course when they do that, in some countries i suppose, they would be legally held accountable for repairs after admitting in public some weakness.
But to get back to your repair, the SDM motor in the lens must be drawing more current than any other lens circuit, i would think. Could it be that the SDM motor circuit is more sensitive to contact performance than the rest of the lens circuits?
Where's my head :-), the SDM uses those two little zoom contacts on the inside of the mount ring to power the motor. I can't believe that those are the sole problem area, as there have been too many posts reporting that internal repairs to the lens had to be accomplished and only certain repair centers had the technology. Also, any number of people have reported cleaning the contacts with no improvement afterward.