No offense, but the cracks are definitely NOT along any area where they where plastic was moulded/welded together from the factory. Each one is a hairline crack and you can see the metallic coil material underneath the unit. Its as though (and Im guessing here) some electrical surge caused the plastic casing to "pop" or swell and it caused the crack.
Whether or not having this metal exposed is detrimental or not to their function is what Im after.
However, you certainly make a good point to check other components first (I changed the plugs out last week- noticed no difference). A check of the fuel filter and regulator is wise and I will do that...
~jason