I wouldn't try brute force. I had a PTO shaft on a tiller that was locked up. I tried pulling on it with the loader (brute force). Didn't work. I sprayed the heck out of it with PB Blaster, put strap through the PTO yoke, and hooked it to a come a long on a tree and applied tension. I let it sit overnight and kept spraying it with PB Blaster. Then, I took a hammer and did a tap, tap, tap. It came right apart.
If spraying oil on it doesn't work, try brake cleaner, carb cleaner or solvent. A soft touch is better than brute force.