I have the same tractor, bought it 1994 with the snow blower and the tiller. Have had very little problems over the years. Use the blower every winter on a gravel driveway--works great except for the very heavy slush.
One problem I did find is that you can not idle the tractor for a long time, the plugs get fouled up and the tractor will not start. I actually took it back to the dealer for repair, they found nothing wrong but the plugs. On the way out the service tech mentioned that you should not idle the tractor for long peroids. Which my wife was doing when she used the 320 to hull water for watering some pines. Never had any other problems now that we run at full throttle.
Martin