NIKKOR 105/2. 5 AI
These are quite good to work on, although i have no idea how to adjust focus. I suspect that the front rim of the focus collar screws off and there are the usual lockscrews inside the collar but haven't proved it (both of mine are too tight and also I haven't needed to adjust focus). To get to and clean the aperture, first loosen the tiny lockscrew in the front cover (you'll have to rack the focus right out to see it). Unscrew the cover and the whole lens assy can be pulled out the front. Undo the front and rear lens group assy's so you can clean the aperture by the dunk method --or take apart completely if your really brave/stupid/need an excuse to kill someone. I DID have a bunch of instructions written on how to insert the lens assy into the main assy, but it's easier for you to work it out i suspect than for me to explain it so it's easily understood. Here's a good headstart though-close the aperture itself right down and set the aperture ring to fully open (2. 5) before assembling.

Canon FD 50mm/f1. 8 (also f2 ?)
Go in through the front on this one. The trick is to flick the plastic nameplate disc out-it doesn't screw out like most. You'll see 3 screws underneath. They hold the main front part AND the front lens groups, so be careful the lens group doesn't drop out before you're ready for it. Look deep inside the focus grip, those 3 screws in the slots are for fine tuning focus if you need to do that. If you are cleaning the aperture blades, then take out the front lens groups and you'll see the aperture assy held by 3 asymmetrically spaced screws-so it can't be put back in the wrong way. Take the aperture assy out and do your cleaning thing. The only trick to reassembly is to be careful that the actuator levers to the aperture assy (2 of) mesh properly. It's easier to see than to explain-you'll get it easy. Test them on the camera to make sure.

TOPCON 135/3. 5
For aperture cleaning, take the front off by loosening 2 tiny lockscrews in the front main barrel. The front barrel complete with its extension hoods then screws off. Pull the entire lens & aperture assy out the front. Now the EASY way to clean it is to remove the front and rear lens groups and dunk the rest in cleaner. If you have to get at the blades as i did to repair one, you'll get access by undoing the 3 tiny screws around the outside. I DON'T recommend that if you can help it though--it's a nightmare getting them all back in. Reassembly may be slightly tricky, as you have to line up 2 aperture actuator levers and the alignment pin & notch. They are all different lengths though so they mesh one after the other. Make sure it is PROPERLY seated on the small alignment screw, put the front parts on and you’re done.

YASHICA DSB 50mm/1. 9
focus adjustment only.
Unscrew the front outer metal cover. The nameplate disc will come with it. Inside the focus grip you'll see the 3 lockscrews that hold the focus grip to the focus drive. Loosen these and do the normal trial and error adjustment with the lens on the camera.

PENTAX SMC 50mm/2 and probably others
Unscrew the nameplate disc with a crutch grip, fingers, your wife's fingernails or a very large sledgehammer and chisel, etc You'll see three sets of screws. Three of them hold the front cover and the other three hold the lens assy in (and lock the aperture adjustment setting). Take the front cover off so you can see deep inside the focus collar-those screws in there are for adjusting focus set. If you need to clean the aperture blades, then take the lens assy out in one piece, unscrew the lens groups off each end and do the dunk-it-all-in-cleaner thing. Several notes-when unscrewing the front lens group, undo the slightly bigger rearward notched ring. That way BOTH rings will come off together bringing the front group assy in one piece. When inserting the whole lens assy into the main outer parts make sure you engage the aperture actuator lever to the right slot inside. It fools me every time i do this lens. You'll have to calibrate the aperture as you put it all back together.

PENTAX super takumar 35mm/3. 5 and probably others
Unscrew the nameplate disc and the three screws underneath. Remove that front outer part and you'll see three screws inside the focus collar. They are for locking the focus. To clean the aperture you'll need to remove the front and rear element groups, leaving the aperture assy inside the main lens housing. Yes, The lens groups are held by all those slot type things, some difficult to get to. . . . . . You'll have to improvise for these. The proper tools would be ideal of course or a home made version. I undid the front ones by getting my brother to hold the outer part while i placed two screwdrivers in the slots and turned them together with some pliers. I strongly recommend you try to clean the blades by the dunk method only. They look like real horrid things to put back together.

CANON EF35-105/3. 5-4. 5
These would have to be one of the worst lenses ever to work on. This one had a partly broken back, almost certainly from a stripped screw (after taking the mount off the back it fell out). I tried to get in several different ways, none of the usual stuff got me anywhere. Under the glued on rubber grip there was an access port to a screw which, I assume, would release the whole focus/zoom assy's and let them come out the front. There was no way i wanted to try that though, as I KNEW that there would be flexible circuits joining everything inside and wasn't sure they were detachable. Every join may have been soldered, not really meant to come apart. After parking it for a few days i had the brilliant idea of trying a self tapping screw to fix it. Maybe the plastic part that the screw screwed into was still there, not broken off as first thought. BINGO, easy! Well kind of easy . . . There were even tons of flexible printed circuits just inside the back!! I managed to lift the main circuit sheet just enough to let me put a new screw in. It went in easy and I could tell by the feel of it that it was going to be nice and strong (I was worried that even a slightly bigger screw may have split the screw hole). I've used the lens for ages now and it's still great.