The rear of my Rainier keeps deflating as though the air has completely escaped from the airbags. I've had one mechanic say it's a leak in only one airbag while another tells me if it were only one side, the entire back wouldn't go down. They've replaced my battery saying it wasn't strong enough to support my compressor. That seemed to work for about a week, but now every morning when I go out, it's completely down again. Any suggestions what this might be? One airbag, a hose, a sensor? Thank you!