I was very happy to find a fairly clean copy of this lens in the junk bin yesterday but when I got home I discovered the problem. The focus ring goes from MFD to about 5 meters and then binds and won't go any further. Where it stops it doesn't hit a hard stop with a clack like at the normal end of the range. It just suddenly gets tight and stops. So I want to take this lens apart and see what's going on but don't know where to begin. The lens butt has about 7 or 8 tiny screws so I'm a bit intimidated, not knowing which ones to loosen. Should I start from the front? Does anyone have experience disassembling this or similar lenses? How complicated is the focusing mechanism? Are there certain things I need to mark or note during dis-assembly in order to get it back together properly? And most importantly, does anyone have any convincing theories on what may be causing the problem? Any help or advice appreciated!