Is it a made in Japan, Mariner? The only letter I have listed after 689 is either an (A) or a (B). The model would help me as well. 689-036668 (90) - 689-231306 (91) model 30M. These are the Japan #'s,yours would be a 90...really a Yamaha,easy to get parts.
I own a model 30ml 689-328778 (86), really though an older Yamaha 79-85. I bought this used 6+ years ago, been great. I've never done anything to this outboard but abuse it...still going strong.
I have the model #'s from 74 - 92...2hp - 60hp...Japanese made Mariners. Its in a zip folder, if I knew how to post it I would...I can send it to people, if you think it would help you in working on these things. View attachment japanese.zip
Guess I do know how to post it...