My 20 year old B2710 has a seized left rear brake. I was changing the front tires and engaged the parking brake lock for safety. I actually never use the brakes as I live on a flat property. So this would have been the first time they were engaged in years. So what do I do? Tried tapping the casing with a hammer. Tried going forward and reverse in low gear. I can move the tractor in low gear with the left rear wheel dragging. Any thoughts? Rich