I recently bought a 48" bobcat ransomes with a 11hp gv400 Honda engine. Its pretty old, but it runs. I used it for the first time on a friends lawn, and it cuts pretty well, but it lacks in power "uphill." My friends yard has a slight incline, maybe 25 degrees, if that, and uphill I had to push it somewhat. Its belt driven zero turn. I dont fully understand the controls because they're not labeled, but it has 4 gears, but they don't all engage. On pavement it runs fine, and to load it onto my truck - I have a f-250- it goes up the ramp like a champ, no prob at all. I'm going to replace both tires, maybe that has something to do with it. Anyone out there have any advice? The guy I bought it from gave me an extra transmition, so I'm wondering if that has anything to do with it. Thank you much.