Im having the same issue too with THQ/Camper Glass flush fit slide windows. Driver's side moves a lot, very loose mechanism that allows the opener to move left/right up/down about 3-4mm, whilst the passenger side glass opening hits the right side of the aperture after closing the sliding door. Given the harsh glass-on-glass connection seems its only a matter of time until the slide door glass cracks after clising the door. THQ slides were fitted by a reputable conversion company who immediately contacted THQ to be told they had a bad batch and are sending a replacement. Feel bad for the fitter as it's not their fault, but these are too expensive to be this flawed.