cub cadet thumping from brake pedal

[bandit79]

lgt 1054 hydrostatic. has a terrible noise coming from under the engine when I release the brake. if I barely depress the pedal I can feel a harsh rhythmic thumping in it. if I set the brake the noise goes away. it drives fine and mows fine but I know it cant be a good thing to make that kinda noise and i'm afraid of destroying something. I noticed a whirring sound from directly under the engine after I shut it off like something is still rotating. when going up an incline it makes a little noise but not much. mower has 155 hours on it and has been well maintained. any help would be appreciated!

 

[bertsmobile1]

Usually this will be a chunk of belt that has broken away so it is new belt time.
Before you order the new one, drop the deck , get under the mower and check the pulleys.
They should spin freely & quietly and have no fractures , blemishes or flat spots.
Slip the belt around a full turn and check it for damage.
Some times a nut or seed pod can get stuck in a pulley and cause the same effect without damaging the belt.
Then some times people win lotto as well.