Rotary Cutter John Deere 1508 Questions

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I recently bought a John Deere 1508 flex wing mower. I'm experiencing some issues with the way it cuts. The seller sharpened the blades and serviced it before he delivered it but it doesn't seem to cut properly. I'm pulling it with a 4020 and I've tried gearing down all the way to 2nd and it still cuts raggedly. The guy I bought it from owns land nearby and his always looks great after cutting. I've rechecked the blades and they are still sharp. One person told me I need to level it front to back and another told me I needed it slightly lower in the front to cut properly. Before I started in doing a lot of experimenting, I thought I would post the question and see what others using a flex wing suggest.

Next question, when I go to sharpen the blades, what is the best way to sharpen them? With a grinder or, as one person suggested, torch the blades down to an edge?

Thanks!