Recently acquired a 20" Murray with the above-mentioned engine. After doing some research, I cleaned the air filter, cleaned the carburetor, replaced the govenor spring, replaced the diaphragm, replaced the primer bulb (I still don't think it's working, but it was dark and I couldn't really see what I was doing), & changed the oil. Parts shop had no govenor idle springs in stock so I couldn't replace the one that was missing from the mower. Have not yet replaced spark plug, but intend to do so tomorrow. Will also remove shroud and examine wind vane mechanism. Blade was in atrocious shape. Will sharpen it tomorrow. Mower started but surged badly. Will mow, but not very well. A vertical tab on the the throttle control mechanism had been bent out of vertical. I bent it back. The entire throttle mechanism seems to move a bit tightly. However, I don't really know how smoothly or freely it should move. Appreciate any comments that might addresss the issue of the engine surge.