No, you can only adjust the tension on the cable by adjusting the clamp on the left side of handle.
Broken Belt
How do you change the blade on a Toro 21" self-propelled mower
How to Change the Tires on Self-Propelled lawn 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.
there a gears in side the box under the mower. also a belt drives the gears. the belt is connected to the shaft that the blade is on.
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.
You may have blown a belt.
6 HP
As a rule! The belt will need to be remove also in most mowers there are gears in the wheels as well. These gears need to be removed. This has been my experience.
blade might be out of balance
6 HP
SAE30