I am just wondering now what will be the result of replacing the starter on a damaged ring gear. I don't think this will solve the problem. Do you think I need to replace the fly wheel also?

OK. If the starter gear will not show damage, but still can be malfunctioning that may the the cause of the damage to ring. No bad noises that I can tell. The starter is the original Bosch. never replaced before. The reason I found the damage to the ring was a broken crank sensor. The chips of metal were sticking to he sensor magnet. Then came the ring turning and when enough metal build up it would hit the magnet damaging the sensor until it broke.

Dear volvito,

Hope you're well. If you're sure the starter is the source of this damage, then the starter is malfunctioning and needs to be replaced or re-built.

When the engine starts to turn under its own power, the starter's drive gear is supposed to retract, so that it cannot contact the ring gear's teeth.

If the starter drive gear does not retract quickly and fully, it grazes the ring gear's teeth. That damages the ring gear. The contact may be slight. But the damage is done. You should hear some unusual noise, at the instant the starter's drive gear touches the ring gear's teeth.

To avoid having to pull the transmission, to replace the ring gear, I'd replace the starter or have a shop re-build the in-service starter.

Hope this helps.

Yours faithfully,

Spook