Plug information is wrong. Most people don't know what "lean" means or how to read a plug. Yours is just fine.
Oil gear is different material as stated. If you try, you might be able to find the original. The newer ones are the performance ones (compared to the old). Yours, oddly enough, looks good.
What does make me wonder is the white stuff in the gear pictures. If that is soft, it might be water in the oil which does not lubricate. If it is hard, it could break down and block the oil flow which runs through the shafts.
Did you find any metal pieces/filings in the cam gear compartment?