The Lawn Chief gas-operated mower is currently built by MTD and sold at the True Value and TruServ Hardware chains. It comes in both a push and riding version. MTD uses engines from specialty manufacturers such as Briggs & Stratton to power the mowers. Repairs parts and kits are available at the MTD website for selected models.
The Lawn Chief is an old brand that has been produced by many different manufacturers. Knowing which company produced your Lawn Chief is critical to knowing which repair parts will fit it. If the original blade is still on the machine, it may have a code number that will allow a parts store to make a determination. Any identifying information such as a model number will also help identify your machine.
You can work on an out-of-warranty Lawn Chief yourself, but it is best to have some mechanical knowledge and experience before dismantling the machine. If you don't have the operator's manual with you, the only way to diagnose a problem may be trial-and-error. You will need to look at the electrical system or fuel system if it doesn't start, the piston and rings if it runs raggedly, and the shaft and blade if it cuts unevenly or the whole machine vibrates excessively.
Spark Plug and Air Filter
The spark plug and air filter are the two easiest areas to check on the Lawn Chief. Most plugs take a special wrench socket to remove them, but the air filter lifts right out. Look at both for cleanliness and wear and tear. It is better to replace an old and corroded part than to repair it. If the mower has been sitting for several years, it is possible that the oil has drained from the cylinder wall. Remove the spark plug and drop a few drops of motor oil down the hole. Clean the plugs, but before you put them back in, pull the starter rope a few times to distribute the oil.
Repair Shop Advice
Taking a Lawn Chief to a repair shop may be the only option for you. Be sure of the value of the mower first. An older mower may cost more to fix than a new one to replace it, and you'll still have an older machine that may have another part fail soon. Describing the problem in detail helps the repair service quickly get to the problem. Be sure that you have an agreement with the service company to give you an estimate once they have broken the mower open to avoid running up a service and parts charge greater than you want to pay.