I have a 1980ish bobcat 630. It is new to me and I am a skidsteer noob. It runs great and functions fine for about 15 minutes or so. Once good and warm it starts to hesitate to turn and eventually won't turn at all. Makes a loud whining noise when trying. I have the manual and it looks like it could be a few different things. But none of the trouble shooting tips say anything about it just happening when warmed up. All the fluids were recently changed and the levels look fine. Any advice would be much appreciated. I just want to try to narrow it down and see if it's something I can fix or if it needs to go to the shop. Thanks Mike