[tinkerman]

I like your check on 6th as you could be drawing dead and he was either trying to check-raise or flat call and get another bet on the end. Of course his 6 could have been paired and he is still drawing.

You could argue to fold if he bets on 6th, but its worth a call on 7th due to the odds of nearly 7/1.

I think his call on 4th is bad because he should get away from the hand cheaply here. By calling, I doubt he could have 8-7 and more likely to be 1-2, 1-3, 1-6, 2-3 or 2-6. He cant have a 5 in the hole otherwise he folds on 5th.