I recently sold my 300mm f/4 and received a complaint from the buyer who described the AF as having a "Screeching and grinding noise and the MF is rough, not smooth". Naturally I refunded his money and he kindly returned the lens by express post... no problems with the transaction whatsoever. I had assumed that the sound was normal for this lens given what Thom Hogan has said in his reviews http://bythom.com/300lens.htm http://bythom.com/300AFSlens.htm The MF sounds (to me) like a ticking of bearings and the AF like a heavy movement of metal compared (of course) to the AF-S of my 70-300VR. It focuses accurately and not all that slowly and the lens produces pretty decent images, used correctly. I'm concerned about it because the buyer said he'd shown it to a Nikon main dealer who'd said that it sounded like a problem where the spindle passed through the lens mount. The clicking/ticking is coming from the focus collar to my way of hearing. Obviously anyone kind enough to reply may say "I'd have to hear it before commenting" (which is perfectly understandable) but before I send it at some cost to a Nikon repair facility can anyone tell me if their 300mm behaves as I've just described. I'm getting on in years and find that heavy gear doesn't agree with my arthritic back and shoulders, this was the only reason for the sale. Please don't think this posting is a subtle ploy to sell the lens... it's not, I'm keeping it but I'd really appreciate anyone who owns a similar lens replying to let me know what their experience is. Many thanks.