While traveling in China, my DA21 got a very loose focus ring. I was able to move the front part of the lens assembly for a few millimeters.
A quick google thought me I'm not the only one with this problem:
focusing ring "play" and viewfinder image shift question: Pentax SLR Talk Forum: Digital Photography Review
Obviously, sending it in for repair was not an option. Since it wasn't under warranty anymore, I took the risk to try and fix it myself. Using a set of locally sourced screwdrivers I disassembled the lens. This was harder than expected but do-able. The screws inside are very small. I started at the back of the lens, unaware of the hidden screws at the front. Working my way towards the front of the lens. As the lens was almost completely disassembled, I found the cause of the problem: three little screws had come loose. No broken parts. It took me about an hour in total to take it apart and re-assemble it.
Now, I didn't know there are screws at the front behind the ring right around the front element and/or the ring with the lens details. I think you can just remove those to fix the loose screws. The rings are glued on. You can remove them with a small knife. The lens should be fixed in 15min. I'm not sure if you can access them like that as my lens was already fully taken apart.
120usd is a lot to fix 3 screws which shouldn't come loose in the first place! All parts seemed to be of very high quality though, just like the outside. Almost all metal.
I'm glad I got my lens back but this shouldn't happen to a ltd lens and shows Pentax has some serious QC issues.
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