One item of kit that is seldom left unsold on the auction field is an Opico GT drier. Straightforward, reliable and well proven, these mobile units have been a familiar sight in the UK since the early 1970s. So, in theory, buying second-hand should be simple – simple machine, simple choice. That’s not quite the case, however, as James de Havilland points out. The reality is that there’s much to consider before coming to a final purchasing decision