Jackson just spoke with Al Sharpton on MSNBC’s “Politics Nation” … and tried to explain why he and his siblings are trying to overthrow John Branca and John McClain. 

“We feel there is criminal misconduct,” Jackson said … claiming the executors had a hand in faking MJ’s will … and Randy believes he can prove it because Michael was in NY on the day he supposedly signed the document in L.A.

Problem is … Randy’s argument has a GIANT flaw … the “mistake” he’s pointing to is based on a witness who merely forgot what city he was in at the time the will was signed.

There are witnesses who saw MJ sign the will … and it has been validated by the court.

But even if Randy and his siblings were to get the will invalidated … MJ’s old will cuts them out of MJ’s fortune too … and it appoints Branca executor.

Multiple sources tell TMZ … the situation is simply a money grab by MJ’s siblings who know that once Katherine Jackson dies … MJ’s money goes in trusts for his kids. Randy and co. will never get a dime.

Randy kept saying they are a family. Paris begs to differ, because she just tweeted, “‘Family’ they said.” Can you feel the sarcasm? And apparently Randy hasn’t read our website … that Tito has already jumped the “family” ship.