This very example was cited to us at a Transport Canada session on developing Minimum Equipment Lists (MEL), last week. It is a very basic example of how a lack of forethought on the part of the manufacturer or modifier, during MEL development, can result in a grounding for no good reason.
It had the group of delegates present mentally going back over designs we've approved in the past, realizing that if our non required modifications quit, even though they are non required, the plane is grounded, unless we get MEL allieviation.