Help! Went to storage site to collect my Puck today.... I hitched up and went to drive off, but the wheels won't turn. The Puck moved along the grass a bit but only because car dragged it, and wheels not rotating at all. Think it might be the handbrake locked on, even though the handbrake lever has been released. Any ideas if it could be this, and if so how do I release the wheels? If not then what else could it be? Thanks