It's because the metal heats up from friction so it expands and seices in place after years of use. Also find all your grease points and give it a nice lube.
You have to heat it up and beat it off. The ditch witch of Birmingham, al is the best. Any problem I have they help me diagnose it, tell me how to fix it, and are always very informative. I'd give them a call from now on. I get free shipping on parts ect. I've never even had to take it to the...