Thanks Grumpy, i know how much you love tecumseh products!!
Pete, do the flow test that grumpy specified and rectify if needed. If it's got good flow and the flow shuts off when you push up on the float, i wouldn't touch it, coz that's probably when you'll damage it. Check the level as above and adjust the tang on the float gently and only a very little at a time. After that i'd suspect that the perished oring you found is the lower one from the emulsion tube. There's 2 on there, 1 at the top of the tube and the lower one you've already found, but at a minimum the lower one needs to be replaced if the top one is still intact. You can pop the tube out with a flat screwdriver through the throat of the carby by pushing down on it firmly, but don't tap or hit it. Once out you can see the extent of the damage to the orings and replace as necessary. With these replaced you should be good to go.
If you get stuck there are some good vids on youtube to help you through.
