How can you test the solenoid to see if its working? Could a bad solenoid cause the motor to rev up high and low? I have a Craftsman lawn mower.

How can you test the solenoid to see if its working? Could a bad solenoid cause the motor to rev up high and low? I have a Craftsman lawn mower.
I am non-mechanical. My 1968 mustang used to do the same thing and I had to fix it periodically. I banged on it with a rock. It worked!