I broke the steering cylinder shaft on my 4310 and I removed that ball joint with a air hammer. I took a flat drift bit and hit on the casting on both sides and it came right off. You could use a pickle fork and a hammer but it would tear the greese boot. Which might be what you are replacing? No air hammer!? get your biggest hammer and hit on one side of knuckle or take two hammers and hit both sides at the same time. Loosen the castle nut but leave the nut on and you will know when it popped free.