It's not like a car, there is no 'ring gear' on the flywheel arrangement. The absolute worse scenario is the stub on the end of the crankshaft has snapped off (happened to a small number of 955s). However in your case, because it's been making a noise for some time, and as Rhead as already mentioned, it sounds like the sprag clutch has failed. Any noise from the starter on 955/1050 engines is a sign there is something wrong (usually as a result of continued starting with a less than perfectly strong battery) and should be attended to immediately. Luckily for you it's easy to access on the 1050 so the labour isn't to bad.