There are two solenoid windings, a pull-in and a hold-in winding. The pull in grounds itself through the starter brushes, and the problem with poor brush contact has existed since the design was pioneered by Delco in the 1940's. I've seen dozens of solenoids changed over bad brushes, with no improvement in starting performance whatsoever.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!