Troy Bilt Mustang XP 42 not moving forward/reverse/turning

[cityboy]

I am new to small engines.
I am just a city boy who moved to the country and am trying to be self-sufficient and learn a lot.
I was gifted this mower from my father-in-law.
I don't know the history of it.
The mower doesn't move. Forward, reverse, or turn.
I have been reading that it could be a transmission problem.
I am installing a new carburetor in a few days, and am also installing a new drive and deck belt.
What could be the problem?
Will I need to put new oil in the hydrostatic transmission?
Or do more than that?
Thank you all for your time.

 

[cityboy]

I put a new air filter, new oil filter, drained the oil, put new oil, replaced the blades, put a new spark plug, drained the gasoline (in case contaminated with water) and put new gasoline in.

 

[bertsmobile1]

First thing to do is download the owners manual
Hidden in it is the instructions for activating the bypass valves.
If it was pushed into a trailer then good chance the hydros were bypassed to make it easier to push.
Next thing to check is that the belt is on all 4 pulleys properly & the tensioner are is holding the belt tight.

 

[cityboy]

Hello, thank you for your reply Bert!
The bypass valves are not activated and the belt is on all 4 pulleys.
However, I do need to replace the belt.
It is very worn so it is a bit loose.
I will check the tensioner after I put the new belt in.