I googled Cub ZRT,ASSUMING it is a cub cadet.
Turns out its a generic name, like SUV if for a common transportation vehicle.
Not being familiar with anything made in the last 40 years, I will sit on the sidelines.
But being 8 years old in todays throw away society, its prolly time for a new lawnmower.
or replacement of the hydro motor on that side if the belt is good.