Hello, I have a 7520 with about 2200 hours, and am about to use the three point hitch for the first time with a 21 ft vibrashank. Discovered the threads on the arms are really frozen from never being adjusted, also the top link. Managed to get it freed up, but the arms are stumping me. Don't have enough of a vise to hold it and crank with a pipe wrench and cheater. Soaking overnight with jd penetrating spray, but...Any suggestions?