I have a 600/4E FL that has barely a trace amount of tripod collar play such that when mounted, rotation is slightly sticky due to the front weight distribution. Play is so slight that I only detect it when pulling the lens out of my Tenba long bag by the tripod foot. Slightly pushing up on the front section of the lens offsets the weight distribution and allows smoother rotation. Are there any screws covered under the collar post that can be tightented to fix this issue? It's certainly not bad enough to send to Nikon and pay several hundred $$ for service including shipping. Of course this may be perfectly normal over time when using this type of lens.