I was given a lens that works perfectly, just one of the decorative inner plastic rings has come loose inside the lens. It is immediately behind the front element and should be an easy fix, but for the life of me, I cannot figure out how the front element comes out. Wondering if anyone had any ideas here. I can usually get into just about any lens, this is my first stumper... There appear to be 3 very tiny allen screws, but when I measure where they are located compared to the front element, they appear to be behind the element. I have tried unscrewing the front element with both a spanner (tried both directions) and I used a rubber deal pressed into the lens to provide grip and tried twisting both directions (did not harm the glass at all). It will not budge.
Lens: Tamron LD 175D/75D 200-400mm F/5.6 LD IF AF Lens For Canon
