Dead battery perhaps. I'd get it tested first at a shop. While it's being tested, verify ALL wiring via continuity. Is it 6V/POS GRN or 12V NEG GRN? Root cause problem solving is the ticket -not to just start replacing parts willy nilly. You don't tell us either but is it a 9N/2N model or an 8N model? All 9N/2N models used a 1-Wire Starter Motor with NO Solenoid. The 8N introduced the 3-Wire Starter Motor with the Solenoid. Get your essential manuals and wiring pictograms out.