Of course my only disassembly experience was with the Ford style solenoid configured for use with the trim and tilt. Once I popped the rivets for the bottom plate there were only two separate parts inside. One was the center armature and the spring it rides on. When the solenoid is energized, the field around the inside of the solenoid case is magnetized. This drives the armature (against the spring tension) to make contact with the two primary metal lug contacts inside the case. The main current now travels from the lug hooked to the battery, across the armature inside the case, to the contact for the lug with the cable that goes to the starter or tilt motor. When the voltage to the energizing post (S) is cut off, the field de-magnatizes and the spring pushes the armature back away from the primary lug contacts inside the solenoid. It was at those lug contacts that my armature was not making contact until I lapped them. This was the case even though the armature contact ledge and the lug contacts were clean with no signs of any burning or distortion.
The differences between the tilt solenoid and the starter solenoid are several fold. First of all the mounting bracket for the tilt does not ground the solenoid like it does on the starter version. The other is in the two small posts on the front of the solenoid. I think that the letter designations for the posts are identical between the two. I think that the one on the left marked "S" is the energizing connection for both solenoids. For the starter version, the one on the right, marked "I", delivers a full 12 v when the solenoid is energized then shuts off when the key or switch is released. On the tilt version, that post becomes the ground for the the (S) energizing terminal. It never carries voltage.
That being said, either one is simple to diagnose if one knows what the different connections are for and how it works internally.