Have you seen this site: Maybe not a parts manual but various things that might be of interest to someone working on a TN….
http://www.pochefamily.org/outboard/
Then….a member here offers a TN=28 Parts Manual on an earlier thread
https://www.aomci.org/forums/topic/1953-johnson-tn-28-carbon-seal-assembly/
Then…..another site has what appears to be a complete Parts Manual for the TN-28…..in jpeg form…..page by page
https://www.tinboats.net/threads/1952-johnson-5-horse-tn-28-mechanical-rebuild.35989/
I went and compiled those pages into a PDF. Not the best scan quality from the tinboats images but they should be OK until a better quality one comes along:
https://www.aomci.org/wp-content/uploads/2023/07/TN-28-Parts-Manual.pdf
