Some Kind Of Motor Problem

" My bro in law has what I thi

" My bro in law has what I think is a 1962 Evinrude 15 hp (the last #'s in the serial/model # string is 62) Anyway, we were out this weekend and the motor made a terrible noise. We thought at first it was backfiring, but upon closer listening and stuff, we now think it may be something in the drive. It sounded like a knock, or clunk and the gear shifter would kind of jump when it did. It almost sounded like the drive mechanism would hit a bad spot, then thunk a time or two, then catch and go. The noise was random but frequent.
We don't know where to begin looking for a problem, or what to do to look. We don't want to tear up anything. Any help would be appreciated. "

" There was no 15hp manufactur

" There was no 15hp manufactured in 1962. The serial number does not designate the year. What is the Model Number? The clunking you hear is in the lower unit. It is jumping out of gear, then right back into gear..... improperly adjusted shift cable if using remote control cables, or/and worn gear lobes and shifter dog lobes. If using remote cables, check and re-adjust if needed. If cables aren't being used, the only cure would be to tear the lower unit down, find the worn parts and replace them. (Joe - 30+ years with OMC) "