The spindle will have a blade brake being whenever the deck is disengaged. In order to spin freely without the brake being applied you must remove the belt from engine's PTO pulley and then engage the PTO lever.
A belt twisting is usually from over heating which a badly worn belt slipping in the pulleys would cause this. Also the wrong belt size and type can cause this. Deck belts must be Kevlar corded. Polyester cords is a no no.
Just note most MTD spindles are usually pretty tough when it comes to blade impacts. The spindle shafts are 5/8 OD which is fairly robust in itself. I only seen a handful in the 15 yrs I have been working on mower to be bent. Usually the spindle housing will break before the shaft bends.
The bearings are 6204-2RS but aftermarket replacements must have additional grease added to them most times. The 6.11" spindle shafts are also available if somehow the shaft got bent. One note here don't remove the spindle assembly from the deck as most the mounting will break off and then you need a spindle assy. I rebuild the spindles which they are still attached to the decks.
