To second California: Why start a situation with materials you KNOW are wrong for the job? Hoye sells an expensive, correct, lifetime starter for this tractor. They also sell the best-option gear-reduction Chinese starter:
Yanmar Tractor Parts GEAR REDUCTION STARTER - NEW!
The pictures up on ebay of the Yanmar starters, including what you bought, are all different than Hoye's image. At least one of the non-Hoye gear-drive starters fits and meshes properly (as best I can tell) on a YM2000 I have, but installing it (by the previous owner) required hacking up the wiring harness so the non-OEM connections on the starter could be used.
This is essentially, in my mind, an assessment of personal values: These tractors are lifetime purchases for the casual user, much like a firearm or hand tool. That is, with appropriate maintenance, they will last your lifetime and then some. Spending some small amount of extra money (comparatively) to correctly and properly put it back to the condition it should be in, with lifetime-quality components, ensures it will continue to be correctly operable for another 30 years or more.
Conversely, a few hundred dollars (at most) less puts the machine back in service, for an indeterminate period of time. It may last 40 years. It may go 3. If one is looking to get it back into service for the bare minimum of cash outlay, do the cheapest starter that properly fits. There isn't a right answer; it's an assessment of values. It's your equipment, obviously you're free to do whatever you like with it. But if it were going into an application where lives might depend on it, or best practices are desired, the old-school "Hergestellt im Deutschland" starter is likely optimal. If treated as a semi-consumable, as, say, tires might be, the correct gear reduction starter is an equally valid choice. Putting objectively wrong gears together is never a good idea.
