Thanks for all the answers, folks. I think my ear is developing slowly but surely - I get stumped less often, and I'm successful more quickly when I'm successful.

Mbo, thanks for the offer - I'll give the song one more try (it's been months since I last tried) and if I fail again I'll send it to you. Heck, maybe I'll just send it to you anyway - if you like Dougie you need to know this song (you were in the "Ready for the Storm" thread, weren't you?).

Michael K, that sounds like a challenging but useful approach. I'll give it a try.

Mudjack, I have a chromatic tuner. How would you use it to find a missing chord? Or do you mean holding the tuner up to a recorded version of the song to see what the other person's playing?

Domenico, I know what tonics and subdominants and dominants are (at least I assume you're talking about 1,4,5), but what are secondary dominants?

Speaking of developing ears... I've never been very confident tuning my guitar so I bought a tuner. Just recently as an experiment I tuned my E string with the tuner then turned all the other strings way down, then did relative tuning by ear - and was very pleasantly shocked to find that on all 5 strings I was right on or very close. Progress happens! Now I'm wondering if I can train myself to tune my fiddle by ear, though hearing a fifth interval is harder than hearing a unison. I did the same experiment with my fiddle, and I got two strings a full octave apart instead of a fifth apart... sigh..

Marion