Hi,
You can figure this out by taking it outside and focusing on something distant. I always use the water tower across the Arroyo, about two and a half miles from me. It is nice and bright and close enough to infinity for me. I have heard other people suggest the sun...but I use the water tower for fear of messing up my eyeballs. If you focus, and then measure from the film plane to about the middle of the lens, you can get an approx. FL.
For sticky apertures and shutters on old lenses, I have had luck by removing the elements, getting into the internals, placing drops of lighter fluid with a toothpick onto areas that look like they need to be free to move, and moving the parts for a while. This loosens up some of the gum and crud from the old lubricants and such. I also stick a toothpick and Q-tip in to pull some of that crud out. I imagine you should relubricate afterward, but I never have, due to lack of specific knowledge of what to use, how much to use, and where to put it. I am sure a camera repair person will have more proper methods, but I have been able to help out some lenses that I would never pay to have serviced this way.
I hate to state the obvious, but don't just squirt lighter fluid into an open hole on the shutter, and make sure you take out the glass first. You want small amounts precisely placed.
