The teeth and the blades are the primary ground engaging parts. The arms could eventually get a little worn and need replaced but it would be rare and take many many thousands of cuts. The rest of the cutter is pretty bulletproof. The Speedplate will need the rubber dampers replaced on a regular basis and the wearblock can wear after a few hundred cuts. The drive motor can require Maintenance occasionally.

Resource: https://mrmanhole.com/product/carbide-tooth-and-roll-pin/