Take volt meter and put it on 20 v dc
Atach black lead to engine ground/negtive. Atach red lead to the starter stud/nut that is at the lower right side. The meter should be around zero turn key on and hit starter button.
Going to guess a few senarios
Solenoid engages but zero volts
Solenoid engages and voltage drops below 10 volts then disengages.
Solenoid engages and motor turns over.
If something else happens we need to know.