Do you get any sort of a "click" or other response as you try the solenoid? Try connecting the jumper to the lower terminal of the solenoid, the big one that goes right into the starter. If nothing happens there, the starter is the problem, not the solenoid. The "pull-in" winding that starts the solenoid operating grounds itself through the starter brushes, so worn or dirty brushes will prevent the solenoid from doing its job. Sometimes a good lick with a hammer on the starter housing near the brushes will get a couple more operations out of a starter with bad brushes, but it's not a permanent fix, just a "get me home" emergency procedure.
Jerry
