The first reference below reports the presence of motor imagery impairments in kids diagnosed with 'clumsy child' or developmental coordination disorder. The second study discovered the important contribution of somtatosensory (body sensation) to motor imagery.
Whenever we think of motor function, we should really think 'sensorimotor' function. All movement is so tightly coupled to body sensation, it's as if they are woven together. Perhaps because sensation has been harder to observe and quantitate, our knowledge in this area lags motor function.
Mental Rotation and DCD
Sensory Processing and Motor Imagery