For nearly 55 years the pipe organ at St. Andrew’s Cathedral in Queen Emma Square has set the mood for some of Hawaii’s most important events, from solemn, spiritual observances to festive celebrations.

“A bishop once told me, ‘You’re the ones who really determine how people experience their faith. You set the stage, lay the platform out,’” said John Renke, music director and organist at St. Andrew’s. “That’s how powerful the organ is.”

President Ronald Reagan and Archbishop Desmond Tutu of South Africa are among the visiting dignitaries who attended ceremonies at which the organ was played. More recently it has been used in the cathedral’s Wednesday noontime concert series.

But now the organ, built by the famed Aeolian-Skinner Organ Co. of Boston and still the largest in Hawaii, is in dire need of renovation, normal wear and tear having taken their toll. More than 700 notes don’t play anymore. Others play occasionally, almost as if the instrument itself decides when to let them sound, forcing musicians planning to perform on it to go to the church early in the day to determine what notes are working and adjust their programs accordingly.

Other notes get stuck, continuing to sound after the key is lifted and not stopping until the entire instrument is turned off and restarted. Even then the notes sometimes continue to sound.

“On Sunday morning I’m here at the crack of dawn, turn the organ on and give it time to think about life,” Renke said with a laugh.

The church hopes to raise $1.5 million for the renovation, which it estimates will take more than a year to complete. To formally kick off the campaign, Renke will perform a New Year’s Eve concert featuring a sonata by French composer Alexandre Guilmant, a 40-minute work that Renke called “a fabulous piece.”

It will be the last time the organ will be used in a major public event until the renovation is complete. Until then it will played only for services and weddings, which require simple arrangements of common tunes. Once the project begins, depending on how quickly the funds can be raised, a small organ will be installed near the back of the church to provide music.

A visit to the organ loft at St. Andrew’s offers a hint of the project’s complexity. Just getting into the chamber requires a climb up a spiral staircase to the tower next to the cathedral, where the huge bellows that blow air through the pipes are housed. This is followed by a sideways shuffle through a narrow walkway onto a small catwalk leading to the main cathedral, and finally another climb up a narrow ladder.

The room is filled with pipes, nearly 5,000 of them. Large, lower-pitched pipes, nearly the diameter of a person’s waist, reach from floor to ceiling, some even bending at the ceiling to accommodate their full length. The high-pitched pipes are about the size of a pencil. Most are metal and cylindrical, but some are wood and square, while others are conical. The pipes create a multitude of effects, from trumpet to flute, clarinet to celesta, recorder to viola and more.

“Each one of these is a musical instrument, basically,” Renke said. “So different metals, different alloys produce a different tone. Some are thicker, some are thinner. The thinner ones produce a thinner tone.”

The room is filled with wind chests containing small bellows and pumps that control the air flow into the pipes individually. It’s all controlled by the console, located on the floor of the cathedral, which has four keyboards of 61 keys each, foot pedals and dozens of knoblike stops that switch on the various divisions, or sets, of pipes.

Almost all of it — pipes, console and much of the bellows mechanism — will be dismantled and shipped to San Francisco for renovation by Schoenstein & Co. Pipe Organs, the company that originally installed the instrument from 1960 to ’61. There the pipes will be refurbished as needed, and, most important, the bladderlike pouches that individually pump air into each pipe will be rehabilitated or replaced. Made of lambskin leather, many of them are broken or no longer function.

Terry Schoenstein, who installed the organ as a teenager with his father 55 years ago and has maintained it ever since, said the renovation will be a challenging project for his family’s company.

“You have to handle everything with kid gloves,” he said. “You can’t just throw stuff around because you’re going to be using it, so you’re not going to be throwing it out, and of course after you’ve made everything right rebuilding, you have to be sure to handle it with kid gloves.”

Schoenstein, 73, has maintained virtually all of the organs in Hawaii’s churches since moving here a few years after the organ was installed. He has been able to keep the organ in service by patching the most commonly used notes. But “you can only tweak anything mechanical or otherwise for so long,” he said. “Eventually you have to put the thing on the bench and rebuild the thing A to Z.”

Once the organ has been restored, Schoenstein expects it to once again produce the glorious sounds and tones appropriate for St. Andrew’s, an Anglican-style cathedral that dates back to the 1860s.

“This organ has a very English to light British kind of a sound,” he said. “Depending on what music you play or under the hands of certain organists, it can actually sound quite joyful. You actually want to sing with it.

“It’s the largest organ in Hawaii, and it was always the organ to go to. There are different instruments in town that have special characteristics and personality, but a lot of people always come back to St. Andrew’s because it’s so versatile.”

Renke, 65, who came to St. Andrew’s in 2007 from San Francisco, knows the power that a cathedral organ has to move people. In 1990, in the days building up to the first Gulf War, he was scheduled to play for a peace memorial in San Francisco at a cathedral that was filled to capacity of about 3,000 people, with many more thousands outside. At the last minute he was asked to play something special at the very end.

“What do you play, at the break of war, (at) an interfaith service with thousands of people there?” he said. He finally settled on a slow movement by Bach. “I started it, and you wouldn’t be aware that there was anybody in the building. And there was a slow, silent march out of the building.

“There’s a lot of discernment in an organ. It can depict huge power or very tender moments. It can be angry, thunderous or delicate. It’s a lot of responsibility knowing just the right thing to play. It can get down to the spiritual level.”