I just bought a used 36" bobcat and it is not going straight I don't know if it's the nature of the beast or A problem. I checked the air pressure in the tires with a digital gage and made a 2 lb correction and it got better but it still moves 6"-8" to the right in about 12-15 ft. of distance . This is on concrete without the blades engaged. It is an older model, belt drive with two new belts. Any Ideas anyone? Would sure like to use it tomorrow but my lines will look like I'm drunk for sure. !'st cut on some new rye grass.