It sounds like a broken record. The power play needs to be better, the power play needs to be better.

Entering Thursday night, the Rangers were in a 2-for-29 skid, and their woes with the man advantage cost them again in a 4-2 loss to the Islanders at Barclays Center.

The power play, which is ranked 16th in the league, didn’t cash in on a four-on-three for 1:15 in the second period, which was bad enough, but the turning point came at the beginning of the third when the Rangers allowed a shorthanded goal.

Trailing 2-1, the Blueshirts had a four-minute power play after Josh Bailey high-sticked Ryan McDonagh with 10 seconds left in the second period, but that backfired. The desperate Islanders battled around the Rangers’ crease and Nikolay Kulemin scored on a backhand pass from John Tavares at 3:03 for the Isles’ fourth shorthanded goal of the season. It was only the third shorthanded goal allowed by the Rangers.

“The third goal was the killer,” said Henrik Lundqvist, who made 19 saves. “We didn’t communicate enough in front of the net. We had five guys back and it cost us.”

Rookie Jimmy Vesey scored 42 seconds before Bailey’s penalty ended to make it a one-goal game again, and the Rangers finished 1-for-4 on the power play.

“There’s a couple plays we could’ve done a lot better,” Mika Zibanejad said. “Sometimes I think it’s easy on the power play to start looking for the backdoor tap-ins and they don’t work out when things aren’t going your way, and then you go in the wrong direction. We didn’t do a good enough job to force them to make good plays.”

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The Rangers killed two penalties early in the first period as Marc Staal went off for tripping at the 48-second mark and Nick Holden went to the box for hooking at 4:15. Holden scored right after that second penalty was killed off to give the Rangers a 1-0 lead at 6:23.

Notes & quotes: Vesey’s goal was his second in two games and second against the Islanders in three games . . . Adam Clendening replaced Kevin Klein (flu) . . . Pavel Buchnevich, a healthy scratch, skated with the spares at the training center, but the Russian rookie wasn’t sulking. He dipsy-doodled for several shootout goals against Antti Raanta, then borrowed a video camera and briefly followed the others during drills . . . Brandon Pirri, with five goals on the power play, was scratched for the sixth straight game. Pirri, an unrestricted free agent in June, scored four times in his first seven games and twice in his last seven games. In between, he had two goals in 34.