yes he has the old belt but you never know if they have the right one on there.when you disengage the blades they stillspin alittle so the belt is either alittle small or the idle pulley isn't going over enough.the belt is cracked and needs to be replaced any way
Like Carscw said, at least on my '88 Lowe's MTD, when the deck is raised, the top of the Blade Spindle Pulley's contact the brake pad's which bring the Blade's to a stop, until the deck is lowered again,, and then they start to rotate again.
You really need to try and find out the Model # if you can. If it were me,, I'd try contacting MTD, and see if they can help. If the mower was ever painted,, they may have painted over the Serial # Decal, under the seat. The previous owner may possibly still have the owners manual. Outside chance,, but never know.
The MTD belt's on mine last a long time,, so it might still have an MTD belt on it. At any rate,, the brake's mounted on the chassis stop's the blade's,, not the belt.
May even still be able to get an owner's manual for it from MTD. I've still got the owner's manual for the '88 MTD/Lowe's.
Good Luck