JFK CTLR EXPERIENCED POTENTIAL CONFLICT AS TFC ON SHORT FINAL WENT AROUND DUE TO MECHANICAL ISSUES AND DEP TFC HAD TO BE TURNED.

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THE B757 WAS CLRED FOR TKOF RWY 22L; BUT WAS SLOW IN ROLLING. THE A320 WAS ON FINAL APCH FOR RWY 22L. IT APPEARED THE REQUIRED SEPARATION WOULD BE MAINTAINED; IE; WHEN THE DEP ROLLS; THE ARR MUST BE NO CLOSER THAN 2 MI ON FINAL; WITH THE SEPARATION INCREASING TO 3 MI WITHIN 1 MIN. ON SHORT FINAL; THE A320 ADVISED THEY RECEIVED A COCKPIT AUTOLAND WARNING LIGHT AND WAS EXECUTING A MISSED APCH. I IMMEDIATELY TURNED THE DEP L AND KEPT THE A320 ON RWY HDG; BUT IT APPEARED THAT LESS THAN THE REQUIRED 3 MI WAS OBTAINED. DEPS WERE ORIGINALLY ASSIGNED RWY 22R; BUT SINCE THE RVR WAS BELOW TKOF MINIMA; SEVERAL DEPS WENT TO RWY 22L AND WERE AWAITING DEP. THEY HAD BEEN WAITING A WHILE TO DEPART; AND THIS SENSE OF 'URGENCY' (ON MY PART) TO GET THOSE DEPS OFF OF RWY 22L CAUSED ME TO TRY TO 'SQUEEZE' THE B757 OUT AHEAD OF THE A320. IN HINDSIGHT; I SHOULD HAVE EITHER HELD THE B757 SHORT; OR ISSUED A GAR EARLIER TO THE A320; TO HAVE PRECLUDED THE SITUATION DESCRIBED. IN THE FUTURE; I WILL NOT LET SUCH SELF-IMPOSED 'URGENCY' CLOUD MY BETTER JUDGEMENT.