Hi, my name is bob, I'm new to the forum. Have 2 acres in oregon. I bought a couple of used commercial mowers that I'm fixing up. Got new carbs for them, and 1 starts right up, runs good, blade engages no problem. But the self propel in not working. If you lift the rear wheels off the ground they will roll but not strong enough when the weight of mower is on it. Any ideas? like to do what I can on my own if/when i can. Any tips would be appreciated, thanks