There's nothing mechanically wrong with the lens. It's my 100-300 Contax. The problem is that a cloud of what looks like haze has developed on the rear element.I removed the rear element and cleaned both sides of the glass which made no difference, then I noticed that the rear lens is actually two thin pieces of glass sandwiched together and the haze is in between the two. Hunting around for a professional to take this element apart and clean it I found someone half-way across the country through a referral of a referral. To the members in the New England, NYC metro area--Could you suggest a place that you were pleased with their work? Also, for my benefit and for interested parties: What's the typical scope of work? Are there various levels of repair? I thought of sending only the rear element, but the repair shop suggested I send the entire lens so that it could be taken apart, checked, cleaned. I really don't want it taken apart. I have visions of my wife's uncle who repaired fine watches for a living and customers would demand their watches returned after being in his repair shop for weeks, but he'd have fifty dismantled at a time with labeled envelopes of their associated parts, some never got their watches back as his workshop had watches in pieces when he retired and later passed away. Attached a picture of the rear element and a picture of Lady Liberty taken @300 from DUMBO park last October and the Lightroom Dehaze filter was probably as high as +50.