I picked up a snapper push not walk behind mower and has a quantum xm on it. The darn thing run like it's at 4000 rpms and knocks and shakes. What can I do to get it back at 3600? Also the body is a 20" with a regular gear drive like on a murray only it's a rear wheel drive. And the wheels are very loose and wobbly. How can I make it a push mower and correct the wheel problem? The wheels go through a rod that's for the transmission and there's two things next to it that hold the wheels. Those are very loose and screwed up. Need some help here.