"MaskedImage" isn't quite the right property you should use for this purpose.
Try instead to extract the mask for each component, as done with the code below:
SetOptions[Image, ImageSize -> 200];
masks = Image /@
ComponentMeasurements[{Degrad, TrucMed}, "Mask"][[All, 2]] ;
GraphicsRow@masks
ImageAdd @@ Map[ImageMultiply[#, Degrad] &, masks]
You should get these masks:
and this recombination:
