By reputation, when the going got tough, Michael Jackson got out.

And even though Jackson was busy rehearsing for a much-ballyhooed series of 50 "comeback concerts" in London, sources close to the King of Pop told FOXNews.com Friday that a series of such a large number of shows was “absolutely not” going to happen.

“In the beginning he only agreed to five, but [the promoters] just kept adding more and more,” music producer Al Walser, who’s known the Jacksons for more than 10 years, said.

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Another source close to the Jackson camp said those around him had serious doubts that he was ever going to get on stage at all.

“Michael was not well at all, he couldn’t live up to his reputation and what others expected of him,” said the insider. “He was never going to perform.”

But Jon Kohan, former head of A&R Records and a good friend of Jackson, told FOXNews.com that Jackson was “so excited” for the scheduled upcoming tour.

"We spoke recently and he was in very high spirits. I wasn't aware of any heart problems, and he was in good health.

"He was so excited for the tour. It really would have been a comeback — he was rehearsing and up to the task."

Jackson was occasionally seen in a wheelchair as he arrived for rehearsals, and there was much speculation on Friday that the pressure of the pending tour — all 50 shows sold out within minutes — contributed to Jackson's deteriorating health before his death Thursday of a massive heart attack.

According to Walser, Jackson had a history of declining health during the high-pressure period of concert rehearsals, and his prescription medications would increase to dangerous levels. In 2001, prior to his “30th Anniversary” concert series in New York, he said Jackson's family “feared for his life” and was forced to intervene with his prescription drug regimen.

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He said around the time he was preparing for the New York shows, “We thought this was it. He was in a very, very bad way and I was expecting to wake up any day and hear that he had died."

“His health gets far worse at concert time, the enormous pressure of the New York shows certainly didn't help his health. As for the London shows, I never believed he could have done all those 50.”

Earlier this year, Jackson was paid approximately $40 million in advance of the London concert series, and in a situation where an accidental death arises, the promoters are generally covered by insurance, although each policy is hand-crafted.

“The concert promoters clearly will make a claim on the cancellation, and its dominoes from here," said Jerry Kroll, insurance attorney for Representyou.com. "It doesn’t stop with how he died; the insurance company (reportedly Lloyd’s of London) is not just going to pony up the money.

“In typical application they will ask if he was suffering any physical or psychological conditions, was he undergoing any form medical treatment or regimen. If they answer yes to any of these they would ask more details, and potentially a medical exam is required.

And given Jackson’s extensive history of health problems, his insurance policy would have been particularly pricey, Kroll said.

“The insurance company is going to be investigating every aspect and question if he was ever going to perform. This is Michael Jackson; he should have had the best health care in the world.

"These are the questions the insurance company will be hiring insurance adjusters to answer: Was it a PR stunt? Was he ever really going to perform? Was it a natural cause of death or something more sinister? Today everyone is in shock; tomorrow the insurance company will launch an investigation.”

The concert promoter, AEG, is facing a reported $85 million refund in concert tickets. According to Billboard, AEG had planned a three-year tour with Jackson, with expected earnings of $450 million.

Earlier this month New Jersey concert promoter Allgood Entertainment filed a $40 million lawsuit in federal court in Manhattan against Jackson for allegedly breaching a contract to play a reunion concert with other family members. According to the papers, Jackson’s manager, Frank DiLeo, made a deal with Allgood to perform in a family reunion concert during the summer and not to perform anywhere before it or for three months after. The papers claim that AEG and the Jackson camp broke the contract by signing on to do the concerts in London.