This is a followup to an older thread that I posted here in November. Basically the focus was slipping and very stiff (close to being stuck). And infinity was at 5m. It was causing problems because the rear element was interfering with my mirror. Well I finally got a chance to look at the lens this week, and the problem was not too hard to find. The focusing ring WAS slipping, AND the helicoid was placed on the wrong thread. All that needed to be done was a quick adjustment to the helicoid and tightening of the screws/washers. So while I fixed the actual problem, the lens was still stiff. I figured the grease was old, so I cleaned the helicoids with alcohol and lighter fluid. The lens was pretty much flawless. This is where my concern lies. I kinda left it that way and put the lens together and it was smooth, BUT I know better, and the threads will be worn out. I bought multi-purpose lithium grease from Canadian Tire today, and I'm wondering how it will work out. Will Lithium grease make the focusing smoother and looser, or should I just leave it unlubed? I know there are better alternatives, but this is all I have at the moment. As well, how much grease should I use, and how/where should I apply it? See this image (not mine) for a good reference on what the helicoids on my lens look like. The gold part on the left also slips off so it's actually 3 seperate rings. Thank you!