1987 911 Carrera Starter will not turn over

Vehicle Information: Model: 911; Year: 1987; Body Type: Convertible; Engine (type, size, modifications): 3.2; Total Mileage: 54.000;

Recently we had a new starter installed and the problem is the ignition turns on but the starter won't turn over ,I hear a ignition click. This is why we got a new starter. Could it be a relay or ignition switch? It starts intermittently. What do think it could be???