Need help identifying Yanmar T220 tachometer part...

[akuhaus]

I have an old Yanmar T220 engine and i need to change the bevel gear inside the tachometer mechanism, but I can't find the part number in the part book.
I also put the photos in my Google Drive here. The gear part circled in green that is made of plastic has been worn out and I need to change it. Can anybody help me identify the part number? It might be contained in an assy. part, but we can't seem to find the right part number. Or can anybody offer other solution? Any advice is much appreciated