Hi:
Sorry for the late reply. I guess our real resident experts are unavailable, so let the third-string give it a try:
Perhaps the clutch bearing is seizing up.
When the blade is disengaged, the motor is allowed to spin thanks to this bearing. If it has ceased to function, the motor is forced to spin against the clutch brake itself. Remove the blade.
The clutch bearing is right under there. If it does not spin freely, you've found the problem.
And WELCOME TO THE FORUM!