I tried to adjust this myself.
Found ti to be pretty easy actually.
- Remove the geared ring around the lens (3 screws)
- Remove the front and midle lens elements (I used a piece of rubber and my hands as wrench)
- Remove the white-cosmetic ring by loosening 2 screws
- The metallic ring there is used to set the speeds, note the position of it. And remove it.
- The problem was some gunk in the gear-system of the speed setting. I used some xylene applied with a hypodermic to losen the gunked up grease. After exercising the shutter many times, I applied some teflon-doped oil (sewing machine type).
The "speeds" ring was also gunked up, I took it away and cleaned it with WD40/xylene
- The diaphragm was clean and mving freely so I didn't touch that
- Cleaned each lens element with cotton swab/windex and then used lenspen to remove any lint.
- Put everything back together and collimat to adjust focus to infinity
- Voila!

Next project... djust a prontor shutter with sluggish slow speeds