Unlock the flywheel from a small engine, like those on a Murray riding mower, using a flywheel removal tool. Access the flywheel by removing the motor shroud and flywheel brake cover. Use a flywheel strap tool to hold it in place and remove the retaining nut. Connect the bolts from the removal tool to the flywheel and tighten the center bolt on the tool until the flywheel pops free.
Removing the flywheel gives you access to the points and condenser of the unit. It is also necessary to replace the sheared pin. Manufacturers use this inexpensive pin to relieve stress if the mower strikes an solid object. Replacing the sheared pin is much less expensive than repairing the damage this type of accident could cause without it.
Sometimes, the flywheel refuses to budge even when using the removal tool. There are several options for freeing it. If there is rust present on the spindle, spraying it with penetrating oil may break through the rust. Tightening the tool and leaving it in place overnight sometimes allows the flywheel to slowly slide free.
Because the flywheel and spindle are made of different metals, applying heat causes expansion that sometimes breaks it loose. In some cases, persistence with a blow dryer provides enough heat without damaging other parts. If using a torch, it is imperative to avoid overheating the flywheel or adjacent parts.