Heavy Landing Check
The whole point of a DI is to ascertain the 'airworthiness' of a machine at that time.
The ATC Gliding School operations were in the main a w-end activity and staff not always present every w-end, therefore there could be a certain lack of continuity in knowledge of events.
When I attended a Glider Inspection course at Swanton Morley it was always made clear to me that 'damage' was frequently difficult to spot unless close attention was given to the areas prone to landing issues, and it should be remembered that this could also include running over airfield ruts left by wheel tracks in the winter. In the main the suspect items were skids and the wheel box, and we usually DI'd in the hangar as it was easier to inspect that area on a flat clear surface (with lead light or torch if required).
Not ALL incidents get reported and there are no instrument recordings to refer to on most gliders therefore a proper DI should include the assumption that the machine MAY have been 'stressed' over the norm.