Oh Les, I sympathise. I simply cringe when someone with bad timing enters a jam. There really isn't much you CAN do. Perhaps the chap learned from tab and simply hasn't had enough experience playing with others, or he may be that rare individual who has great digital dexterity and NO sense of rhythm.

I've found that the very hardest person to teach is one with the above symptoms. If I'm working with someone who's timing is off, first I acertain whether they can hear good timing from a recording. If they can, then it's simply practice practice practice. If they can't then it's practically impossible to help them learn to play with others.

I'm afraid if I was at the jam, I'd just pack up and shuffle off.

Cheers

Rick