Haying season starts today. Are there ways of adjusting a sickle mower to cut better? I have a JD #8 with serated knives. Last year I found the trefoil fields hard to cut. The mower would get plugged all the time. Can you sharpen up the knives, a gaurd? I replaced a gaurd yesterday and the dealer told me to replace all the gaurds and knives if I want it to cut bbetter. It cuts mixed fields fine, just the trefoil field that is a problem. I think the dealer just wants to make easy money.