As your question, how to inspect coil condition?
Not has an exactly method to checking for solenoid coil condition krub, because of not only solenoid coil resistance but still relate with the electricity, ambient temp, etc.
if only for solenoid coil resistance tolerance -> if the solenoid coil resistance run-out of standard resistance as big-gab of tolerance approx. +/- 10% that will be a sign the show that the solenoid coil should be changed.
Sample for DC voltage solenoid coil resistance tolerance acceptable range