I have pictures in the cloud somewhere but it's quicker to do this than find them.
Start here. You want the filter threads to be free of grit. An old toothbrush might help. You need to unscrew the "name ring" with all the engraved writing with a friction tool. You can improvise here. The link above suggests sticking double sided tape to the ring and using an M42 lens cap to stick to the tape. That should work. The ring is threaded into the filter threads. If the ring doesn't move, you can try very tiny drops of penetrating oil if you can get it just on the filter threads. If you lube the name part, it's hard to get the friction thing working.
When the ring is off, you should see this. You want to remove the three screws that aren't in the little cutouts. They are JIS screws, so ideally you'd use a JIS screwdriver. A Phillips #00 will work OK on these particular screws in my experience. These hold on the front barrel. Lift that off.
Now you can see three more screws just inside the focus ring, in an aluminum ring. Continue to ignore the three screws you ignored previously. The screws you want are holding the focus ring to the focus helix. Don't remove them yet. Put the camera on a tripod and the lens on the camera. Point the camera at a distant object. Focus to the infinity stop on the lens. Loosen the three screws. Now you can turn the focus ring without moving the focus helix and changing the lens focus. Turn the focus ring back a few degrees, maybe to the 1 of the 15m mark. Tighten one screw and you can focus further towards infinity. Repeat those steps until you are happy with infinity focus. Tighten all the screws, put the focus barrel back on, put the name ring back on and you're done.
BTW, the photos show the aperture opening at f22. If your opening looks larger than this, you can adjust it while your lens is apart. Set the focus first. Then set the lens to f22 and loosen the three ignored screws. The lens assembly can rotate now. Rotate it until the blades open a little, then rotate it in the opposite direction until the blades just stop moving. Tighten one screw. Set the aperture to f1.7 and the blades should retract fully. Tighten all the screws when both extremes look good.
Similar Threads 
