Ok, no replies so let me give it a try. Is the system serviceable? My Bad Boy has two filters on the unit and a plastic fill tank under the seat for the hydraulics. If the system gets low, it can draw air. This sounds like maybe what happened in your case. If the system has never been serviced, I would say maybe a filter or it has just gotten low due to use. If you look up BBM_service manual online, you will see some good pictures of how to service the unit. I'm not saying the toro is the same but my mower drains from the filters but when I refill the system, there is a plug on top of the drive motors that you must remove and then start to fill the unit in the storage tank. When the oil starts to run out the plugs, put them back in and continue to fill the hydraulics slowly. My mower will hold about 4 quarts before you get oil out the plugs on the drive motors. Once you get oil in the tank, you start the mower with the back end off the ground and place the drive handles to the rear. Go to the back of the mower and push the air bleed handles in and out slowly about ten times each. The wheels should start to turn. Place the drive handles forward and push and pull the air bleeds slowly again. Once the tires turn under their own power forward and in reverse, make sure the hydraulic tank is at a satisfactory level and you should be good. Now I don't know how Toro works but there should be some similarities. What I do know is don't run the system dry. Not only does the oil run the motors but it is also a coolant along with the fans but if the system does not have enough oil, you can damage the wheel motors. I hope some of this info helps but your manual should cover the service if it is applicable. Some units are not able to service but they all need oil. Good luck. By the way, my BB uses 20W-50 motor oil for hydraulic fluid so make sure what yours takes before just adding oil. You could have another problem but with one wheel starting to give you trouble and then the next at a later date, I would start looking at fluid levels and filters. Take Care!
