How hard is it to change the ignition switch on the car?Seems like the ignition switch could be the cause of the starter not disengaging?What is involved?

 

Typically the starter hanging up is a result of the solenoid failing. (It fires back and forth to engage the starter gear to the outer diameter of the flywheel.) I haven't looked at the starter on your car, but if it is like most starters, there area large cylinder and a small cylinder on the starter ***'y. The solenoid is the small cylinder.

 

I take it the starter must have disengaged normally when you pulled the Black/Red wire off of the starter solenoid??
The wire is Black w/Yellow stripe up at the ignition switch. If it is only the electrical portion of the switch that is sticking on start then is very easily replaced with one phillips screw at the back of the lock cylinder. If the Lock cylinder is 'mechanically' sticking on then the entire cylinder is removed by knocking out the the two breakaway bolts on the top part of the cylinder. Add a hammer and sharp chisel to the tool list for that one.