Goes into second with a clunk, then with any throttle slips out into neutral. I also tried going thru the gears on the work stand and it will stay in second with light throttle, but rev it up and it pops into neutral. I think "slips" is a better word, because it doesn't make any noise.
1st, 3rd, 4th, and 5th seem OK. I am going to check the pins on the shift shaft next week.
I hope this doesn't require an engine tear-down. I don't need a boat anchor!