Four Tries

On this hand (also given in Counting Winners), I am asking what went wrong in a very literal sense and am going to go through the play of four declarers. But let me first give some figures that might be of interest. The hand was played by 64 pairs, 46 of them in hearts. (Ten were in no trump and the remaining 8 were doubled partials by E-W, mostly with disastrous results.) Forgetting the contracts for the nonce, here is what declarers picked up in heart contracts: Seven made 10 tricks, 18 made eleven, twenty made 12 and one lone figure made 13. One!
A Q 7 5
K Q 7 3
K 6 3 2
3
8 2 J 10 9 6 4
10 8 4 5 2
Q J 10 9 5 4 8
6 5 K Q J 8 2
K 3
A J 9 6
A 7
A 10 9 7 4

It's hard to understand how anyone made only 10 tricks. With hearts 3-2, one would think anyone would fall into a club ruff later if he doesn't take one early. But I didn't want to examine those hands, nor those who made eleven tricks. I wanted to see why declarers who'd made 12 tricks didn't make the 13th, which virtually falls into one's lap. To satisfy my curiosity, I picked four declarers at random -- and found 4 different paths to 12 tricks. Only one ran through 12 tricks in a businesslike fashion, including the cashing of his last trump, but locked himself into the wrong hand, thus missing his squeeze. Here is his end position:

A Q 7
------
K 6
------
------ J 10 9
------ ------
Q J 10 9 5 ------
------- Q 8
3
J
7
10 9

At this point, declarer cashed his last heart, sluffing a diamond, and went to the king of diamonds. He's now locked in dummy, and East can discard his last club with impunity. Declarer would have had his squeeze if he'd only reversed tricks 9 & 10, going to the king of diamonds and coming back to his last heart by way of ruffing a diamond. (It's effectively the same play as leading the heart, sluffing a diamond.) This puts him in the South hand, when all red winners have been played, with an entry to the North, which makes the squeeze operable, and East will have been squeezed at that point. If the 10 of clubs isn't high, go to your spades, and you will be given a pleasant surprise.

The second declarer started out well enough ruffing clubs, twice, returning to the closed hand with the diamond ace, but tried his diamond king in an attempt to get back, instead of coming to his spade king. This was ruffed, and that wiped out any 13th winner. However, this declarer got that trick back when RHO led the queen of clubs after the ruff, giving declarer a third club ruff, which he can't do without that loss to a trump for lack of entries.
Declarer could cash his king of hearts and now re-enter the closed hand with a spade or a diamond ruff. His winners were seven hearts, one diamond, one club and three spades.
The third declarer got a ruff from the other side of the table. After ruffing a club, this declarer cashed the K Q of hearts, then came to the closed hand to try for a second ruff. West could ruff higher than dummy, however, so that wiped out this declarer's chance for 13 tricks. That declarer also got his trick back, for there was still a trump in dummy to ruff the fourth round of clubs (the fifth goes on the queen of spades).
Which brings us to the fourth declarer, who was granted his 12th trick only by a very inattentive opponent. This declarer (with a club opening lead), took a round of trump with dummy's king before ruffing a club. Actually, he has just enough entries to recover from this: diamond to the ace, ruff a club, spade to the king, ruff a club, overtake the queen of trump with the ace, cash the jack, then go to the king of diamonds and ruff a diamond coming back.
But declarer continued in what should have been a disastrous pattern. After the second club ruff, he actually had two ways of recovering: to overtake the queen of hearts, then draw the last trump with the jack, or to cash the king of diamonds ruff a diamond, since the person short in diamonds is also short in hearts. Now, particularly on that second line, where he's using up his diamonds, he too would have fallen into the same squeeze for 13.
Instead, he cashed the ace of spades! That destroyed the communication between the hands, not completely, but enough. Now after cashing the queen of hearts, he tried the queen of spades, but that was ruffed and a diamond went to his king. Here is what the table was looking at:

7
------
6 3
------
------ J 10
------ ------
10 9 5 ------
------- Q
------
A J
------
10

Declarer, in dummy, ruffed a spade, cashed the ace of hearts -- and East sluffed his high club to save his high spade! Declarer had just shown out of spades on the previous trick!
What went wrong on this final play-through is fairly self-evident. There was the trump lead to the king. As outlined above, he can recover from this, but the lead nevertheless indicates that he's taken his eye off the ball. He's not thinking, "get two club ruffs and draw trump", and this fuzziness of thought was to manifest itself in a moment. The turning point, where he can't recover with good defense, came at trick 7 when he cashed the ace of spades. Now he can't use the queen, when it should have been evident that he wants to get out the trump and then cash his spade honors. He has an entry, both to his hearts, and then back to the spades, and this should have proved to be a fatal error and would have except for an overly inattentive or overly generous opponent.