There is an urban myth that the Ruger MkII is hard to clean. This is completely wrong! It is pretty easy to take apart, not too hard to clean, and only hard to get back together if you don't know the *SECRET*. Without the secret, even strong men turn pale at the thought of having to reassemble a Mark II, and women have been known to use most unladylike language at the "all back together but the !@#$% bolt won't pull back!!!" syndrome. (Ruger doesn't know the secret - otherwise they surely would have put it in the Instruction Manual - or would they have? :-)
I learned the secret from Ram-Line, and they probably would send you a copy of their illustrated little pamphlet (well, it's just two sides of a piece of paper, but it has several photos as well as the text.) I'm sure they would send you a copy if you sent them a couple of bucks and a nice letter asking for a copy of "Reassembling a Ruger Mark I or II - in 60 Seconds or Less!!".
However, perhaps I can give you enough clues so that you can master this. I'll also give some other information. All of this is what I do with my 5 1/2" bull barrel stainless steel model. I have a few special tools for cleaning - a little pull tool, made from a paper clip, with a circle at one end to put my finger in, and a bent end that can pull out the end of the housing latch. I also need a plastic hammer (small mallet) to remove and replace the barrel/receiver on the grip frame. Then I find that some Q-tips and wooden toothpicks are extremely helpful in removing all the grime from the recesses and crevices. I use Hoppe's No. 9 for cleaning.
The disassembly given in the Manual works just fine - I find that I always need the plastic hammer. You can then clean the receiver/ barrel easily, using the Q-tips and toothpicks in the hard to reach places of the receiver. The bolt comes apart easily in steps. You can always take the recoil spring assembly off the bolt and clean it with a rag. The other dirty place will be the bolt face, and a rag or small brush and a toothpick make quick work of this. The firing pin probably doesn't have to be removed every time, but it comes out easily after the firing pin stop (a cross pin) is pushed out. *Remember to replace this* if you take it out. Then the firing pin, its spring and a little rebound spring and its support come out and are easily replaced. If carbon accumulates along the firing pin, that can create enough friction so that the hammer won't hit the cartridges hard enough to fire them. So you may suspect this if too many misfires occur. The only other disassembly possible is the Extractor assembly - see below for details on how to do this one. It shouldn't have to be done often.
Now the bolt is clean, and reassembled, and the whole gun is to be reassembled - remember that this part can be done in 60 seconds. With the hammer horizontal put the receiver/barrel on the grip frame - and hit the front of the barrel with the plastic hammer if necessary - I always have to hit it, and give it quite a good smack. Before disassembling, note how far back the receiver has to go compared the the back end of the grip frame, and this will give you better guidance than the vague words in the manual.
Point the muzzle up, pulling the trigger so that the hammer falls back and the hammer strut is hanging back, and put in the bolt. Now you want the hammer back forward - so either tilt the muzzle down and pull the trigger, or reach in with a small rod or screwdriver and push the hammer forward while pulling the trigger. Now insert the bolt stop pin through the holes in the grip frame and receiver - it goes in kind of hard because it has to push the back end of the recoil spring assembly out of the way. If it won't go in, the barrel/receiver may be just short of all the way back and needs another smack with the mallet!
Now comes another trick - tilt the barrel up at about 45 degrees, and notice the little hammer strut swinging free - you want it to fit into the small canyon shaped depression on the forward top face of the mainspring housing, just below where the bolt stop pin latches. You swing in the mainspring housing so the hammer strut goes in there, and then the mainspring housing fits into the grip frame easily and you latch it in place with the housing latch.
That's it! Pull the bolt back, and it should come all the way back, and when released it should return to battery and cock itself. (If it doesn't come all the way back, you have to remove the bolt and try again.) I then put a couple of drops of Breakfree CLP on the bolt and the bolt rails.
Some more information - Ram-Line's address is Dept 1105, 406 Violet St., Golden Co 80401.
Here's how the extractor assembly can be removed from the bolt and be replaced.
There are three pieces making up the entire assembly, a spring, a "rod" shaped piece which fits into the spring and bears on the extractor proper, and the G shaped extractor which actually grabs hold of the rim. The rod's end is a cut-away cylinder which holds in the tail end of the extractor, and the two must be pushed apart before the extractor can be pulled out. I did it by taking a small (about 1/16") but strong screwdriver, and pushing the rod back into the spring. After it is pushed down nearly 1/4", then there is enough room between it and the bottom of the extractor that the extractor can be pulled out easily with the fingers. This pushing down the rod and holding it down is the tricky part. There isn't much room to maneuver the screwdriver. Then release pressure on the rod while holding a finger over the end of the bolt so nothing springs out and gets lost. The rod and spring can then be pulled out with the fingers (perhaps with a toothpick.) It goes back together even more easily.
However, note that there is little benefit of removing the extractor. The bolt face can easily be cleaned simply by pushing the extractor aside, and there seems to be very little accumulation of dirt in the extractor assembly.