6 HP
6 HP; it is in the model number - 21" 6 HP
How to Change the Tires on Self-Propelled lawn Mower
How do you change the blade on a Toro 21" self-propelled mower
Self propelled mowers are not self driven. The mower has a safety switch which does not allow the unit to turn on itself. A person is required to turn on and steer the mower.
I've never owned a self-propelled mower, but I would think there would be a lever to engage the wheels for self-propulsion. If the lever is in neutral. I would think you would be able to pull the mower backwards on all four wheels. If there is no lever and the mower is self-propelled at all times, you would have to raise the wheels that are propelled in order to pull the mower backwards.
Broken Belt
6 HP
blade might be out of balance
SAE30
6 HP
10-30 or 30
If you bag your grass clippings a rear wheel drive self propelled mower is better . As the bag fills up it adds weight to the rear , which tends to " tip " weight off the front wheels