54 GMC 100 series 12-volt system

My starter won’t turn over and I’m wondering if the starter has gone out, would appreciate any tips.

For some period of time, it has been difficult to get the starter to turn over. I would depress the foot switch and nothing would happen. If I depress release depress release several time, it would eventually “catch” and crank the engine.

Yesterday it would never catch. I took the foot start switch off and touched the cable directly to the copper contact on the top of the starter, nothing happened. Thinking that perhaps the cable was bad, I used jumper cables to make the connection. One end on the positive side and the other side I touched to the copper contact, again nothing happened. Makes me think the starter is dead, is it? Any additional test I should try?

If I need to purchase a new starter, should I go with a 12 or 6 volt?

As a side note, not sure this as anything to do with it but… The foot switch was somewhat difficult to depress but yesterday it got a whole lot easier to depress. Right before it got easier, I felt something give, had to describe exactly what it was, but it is easier. Looked around and found nothing out of the ordinary. And since I have bypassed the foot switch, I don’t think it is connected.