Questions (at the table, I got this wrong):
- Do you go up with Jack of spades, or duck?
- What's your line?
Who has the 5-card spade suit? Assuming that North had a choice of major leads if he had 3 cards in each, it is more likely that he has the 5-card suit, and that the 3 is his 5th highest card.
Given that North has the 5-card suit, he would have led the King from KQ10 (internal sequence). So, South has one of these three honors.
Who has the 10? The odds are 4-2 that North has any specific card. So, let's put the 10 of spades with North. Now, do you go up with Jack of spades?
Interestingly, it doesn't matter because you are going to duck this trick and win the spade continuation. Otherwise, you have no safe way of rectifying the count.
Having thus rectified the count, can you win all the remaining tricks on a squeeze? I'll leave it as a puzzle for you -- you can try to play out the hand on BBO. Post your answer as a comment.