I regularly take apart lenses and could easily do this with yours. You have to first remove the center logo ring around the front element. I have said before that only Nikon had the sense to go easy on the lubricant; there is little to 'dry up' with their lenses. If you could see how much gunk is on your helical you would be disgusted!

If you are by any chance near Philadelphia I could do this for you for about five bucks. My land line is 215.569.4949 in case you have further questions.

The 'normal' lenses, from any manufacturer, are especially easy to take apart in most cases, especially the Minoltas and the Pentaxes. The Canon are a bit troublesome. Most M42, as you have, are rather straightforward. The problem here is usually not the helical, per se, but rather the thin thread circular disk that mounts the helical to the body. That thread needs to be thouroughly degreased. - David Lyga

SORRY DJ, you are across the pond!