Old JD ride-on, I just bought it. Engine runs great, idles a bit fast. Mower cuts for a while (up to 5 minutes today), then blades stop turning (engine keeps running fine). The PTO switch doesn't move (stays in ON position). I can turn PTO switch off then on again, and mower will engage again briefly. Peeked as best I could at belts, they are not frayed and seem tight.

Could be the electric clutch.