First double check the key-switch to be sure the solenoid is getting a full voltage signal.
Did you wiggle and/or keep twisting the key to start? Sometimes a tap with a screw driver or lightly with a hammer will unstick the solenoid too. It is indicative of a sticky solenoid in need of replacement.
If voltage is good from the switch change out the solenoid, They can stick once in a while as they are in a nasty environment.
Dave Neptune
