Ok so I kept getting errors because my ext was lose as hell when I put it on my 300mm Sigma Prime. So a few days ago I purchased some of those small screw drivers thinking there was a screw or two loose. Well I got them and proceeded to tighten the screws, the bad part they were all tight! I didn't have time to think about it on friday so today when I sat down and thought about it more I decided to take off the screws. So I took off the screws and peeled back the metal area to see if there were screws underneath I was missing. Well it turns out that beneath the metal top area are about 4 screws that keep it together (the lens is made of two sides). They were almost entirely off! I mean they almost fell out lol So I screwed those tight and it was like the first day I got it! I am so relieved to be honest. I thought I wasted 200 bucks. Turns out it was an easy fix. Here is an image of the screws and set of screw drivers I purchased {}