
http://www.dchome.net/forum.php?mod=viewthread&tid=1197120
(in Traditional Chinese)
So, he dis-assembled the whole lens down to the chamber that holds the aperture blades and re-assembled all of parts for the whole lens. He succeeded to repair the lens finally! Good job, guy, you are really brave enough and brilliant! :-)


But yet somehow unfortunately, since the user did not have the required tool to screw in back the front lens cover plate, he was forced to drill two holes onto the plate so that he could grip it firmly for screwing with his forceps. He refilled the gaps at last, so as to prevent dust and dirt coming inside the lens again.

Nonetheless, the lens was reported to be very vulnerable to dust particles for getting inside, which is also yet another problem of this lens model.
Related:-
DA40/2.8 Limited Disassembly