The Reasons Your Lawn Mower Isn’t Self-Propelling. Don’t get distressed when you realize that something’s happening to your lawn mower. There are a number of things that you can investigate in order to ensure that you become aware of what’s causing your lawn mower problems. When you know what is causing the problems, you can then learn what you should or shouldn’t do and then you can be more empowered with the knowledge to fix it. We’ll show you the main reasons that your lawn mower isn’t self-propelling.. The Wheel Assembly is another possible cause: There are a set of gears from the wheel assembly, which engages with the transmission drive gear. If those transmission gears get worn out, they won’t be able to engage the wheel assembly and they should be replaced.. The Transmission may be the problem: The engine’s crankshaft is connected to the drive belt, which is powered by the drive belt. You have to determine of you have a defective transmission by observing it while the mower is running – if you see that the lawn mower wheels aren’t turning, but the transmission pulley is spinning, then it means that the transmission is defective. REPLACE it, because it cannot be repaired.. The Drive Pulley may be another cause: This is the pulley that connects to the engine crankshaft and if it is broken or worn out, it would stop the transmission from engaging the wheel assemble. Make sure you check the drive pullet for damage and if there is any, you need to replace it.. The V-Belt may be the problem: It is the part that rotates the drive outlets to drive the lawn mower wheels. If it gets broken or even worn out, it will stop the lawn mower wheels from turning. Take a look at the V-belt for damage and it is indeed defective, you should have it replaced.. If you are looking for small engine repair services in Ottawa, mobile car battery boosting, lawn mower and lawn tractor repairs and tune-ups, or snow blower repairs then give us a call to book your mobile small engine repair today. We fix, repair, and tune-up small engines such as lawn mowers and snow blowers and home generators. The best part is that we come to you so no more waiting in line or traveling back and forth to fix your small engine equipment.