A drawback to the Ramsbottom type was its complexity. Poor maintenance or mis-assembly of the linkage between the spring and the valves could lead to a valve that no longer opened correctly under pressure. The valves could be held against their seats and fail to open or, even worse, to allow the valve to open but insufficiently to vent steam at an adequate rate and so not being an obvious and noticeable fault. Mis-assembly of just this nature led to a fatal boiler explosion in 1909 at Cardiff on the Rhymney Railway, even though the boiler was almost new, at only eight months old.