Hi. My Hoover Windtunnel has been acting up recently. So I don't know if this is normal, but when the vacuum is in the upright position, self propelled is on, and when you push on the handle, the wheels move, making a weird sound. It does this also when its reclined in vacuuming mode. Its not the squealing noise that occurs when you pull it back, its a different noise. Help, please!