1966 Evinrude repair and parts question.

[66KingFisher]

We've got an old 66 model Evinrude 40hp with push button shifting, that runs like new, but has started jumping out of gear under mild acceleration....we've been told something called a "clutch dog" needs to be replaced in the lower unit.....Any of you guys got experience in replacing one of these.....what about just finding a new or remanufactured part for that old motor? I can't find much online, and Evinrudes own website doesn't go back to 1966......are we screwed or is this repairable for a couple of old DIY'ers.....or do we need to find some old marine mechanic that knows old motors that might be able fix it for us...that is if parts are available?......a local marine mechanic I talked to here said most guys don't work on outboards older than 20yrs.

We would appreciate any input as to what our options are.....shy of purchasing a new motor, which really isn't an option for us.