When my 3320 sits for a couple days the left rear wheel sticks. Takes a fair bit of "rocking" the tractor to unstick it. I just had both brake cylinders all apart and cleaned up. The right brake works perfect. I took it for a drive and held the left pedal down slightly to drag the brake and shine it up. Are these brakes in oil or are the dry. It's a 1996 3320. Any idea's what could be going on? Works excellent other than this problem. Thanks.