Auto Parts: Chevy starter, chevy starter, chevy 396

Question
I have a Chevy 396 BB with a powerglide trans.  I am using a start button and on/off toggle.  The starter will not disengage when the start button is released.  I have shimmed it from 0 to .080.  No luck.  I am running out of options.  Any suggestions before I start replacing parts.

Answer
    It sounds like an electrical fault in the starter, to me.  Pull the starter off, but leave it connected to the wires and cable.  Then, operate it with the push-button.  If it does the same thing, then something inside the solenoid is causing the contacts to stay together.  At that point a new (not rebuilt) solenoid is in order.  And make sure that the wire that goes to your push-button is hooked to the "S" terminal on the solenoid.  The other terminal is used to bypass the ballast by going direct to the coil.  If you had them reversed, and the ignition switch was on, you would get the same effect that you are describing.  I guess you should check that first.  It is a weird way to build something, but the design of the solenoid works great if it's wired correctly.  If it's wired backwards it acts as a self-latching relay and won't shut off if the ignition switch is on.  This same defect could occur internally if a rebuilt solenoid (which is what you get when you buy a rebuilt starter) was wired incorrectly by whomever rebuilt it (which, these days, is going to be someone in some third-world country who has never seen a Chevy unless he watches NASCAR on his satellite dish).