Awesomesauce!!!! It friggin works!!! My Pentax 16-50 f/2.8 lens failed completely for the third time this morning...it started about a week ago, focusing really slow, or not finding focus lock. I found this thread on Pentax Forums: http://www.pentaxforums.com/forums/pentax-slr-lens-discussion/130429-diy-supersonic-drive-motor-repair.html about a week ago coincidentally, and put it in the back of my head in-case my fears were realized again....The first time the motor was replaced by Pentax, out of warranty, the second time it failed within 90 days of repair, so it was under warranty, then this morning it went while out shooting landscapes. Well I decided that had nothing really to lose this morning, since if I screwed it up, it was going to go in to Pentax anyway, so I would button it back up, and send it in. I am happy to report, after about 20 minutes of work (I am a Navy Sonar Technician, so I have a lot of electronic repair experience), via the DIY procedure, my 16-50 focuses again. Saves me $400, since it is not under warranty for the last repair anymore. Sweet.

The only things I would add to this DIY would be a bit better picture of the weatherseal position on the lens once it is replaced, or before it is taken off...my haste caused me to not really pay attention, and the first time I put it back on, I had it upside down. Also, getting the 6 gold contacts to line up into the holes during the re-install can be tedious. Also, I would recommend the user of this procedure looks at the DOF scale on the lens while they are turning the SDM motor back and forth, as to not over-turn the motor/gearing. Un-attaching/re-attaching the spring for the apeture can be troublesome also. But if you get it on either with the spring hook up or down on the apeture hook, it will work either way, so take it where you can get it.

Below is the link to the procedure for the fix, it is pretty good, with decent photos, and descriptions.
http://bangmedia.no/pentax/sdmfix/