Originally Posted by tpasztor
Paint thinner in carb and muffler. Work it slowly back and forth until it breaks loose.
plastic parts and some rubber o-rings and seals will not like this.
most likely the engine is frozen due to the oil that was stored in it gumming up the work. heat is your friend. stick it in the oven on about 125 or use a hair dryer or a heat gun on low and see if you can get it to move.
you may also remove the backplate and check the bearings for any rust or corrosion. if the engine sat up in storage for that long i would be surprised if the bearings arent rusted stuck.