I had to recently replace an oiler on a Poulan 2150. To get the clutch off you will need to stop the piston from moving. I guess the old school way to do that is to take a piece of rope, I had like a 3/16 inch piece, something that you can shove down the spark plug hole that will not scratch the piston or cylinder. Stuff it as much as you can get in, then pull lightly on the starter rope until you feel the resistance and it should eventually stop. They make a piston stop which is basically a spark plug looking thing that goes down in the cylinder farther than a spark plug and will stop the piston.
Now, on to the clutch cover. I didn't have the tool for taking it off, so I used a pair of needle nose pliers and an adjustable wrench to remove it. Once the piston is stopped, it should unscrew fairly easily. I think it unscrews opposite of the regular way, clockwise I guess. The clutch cover probably says which way to remove. Once you get it loose, then you will probably be ok.
Take some compressed air and blow through the tube. The other thing you may want to try before getting the clutch off is to take some kerosene or gas or something and pour it into the tank after draining the oil and swish it around some and see if it will unplug anything that might be clogging. You can also run the saw with the cleaner in the oil tank a bit to see if it will start flowing (bar off). Be careful if using gas or kerosene. Flammable. Also, if it doesn't start flowing within a short period, I wouldn't try it for more that 30 seconds or so at most, then you probably have a bad oiler that needs replacing. Take the oiler out after you get the clutch off and check it. The little gear in there should move freely. Then to replace it, my part was like $8.00 and it was easy to get back in.
