How do I change PTO drive shaft belts for a Grasshopper 725K?

The images I see look to have a keyway shaft, so the obvious thing would be that they are not lined up.

Parts schematics. Anything missing?

https://www.google.com/search?q=lt1050+parts+diagram

See if the videos help. They seems to be problematical.

https://www.google.com/search?q=LT1050+PTO+clutch+replacement

To replace a transmission drive belt on a Cub Cadet LT1046 you need to remove the deck, preferably put the front wheels up on blocks or stands, unplug the PTO power (directly under the engine, which can be a pain ) You need a 5/8" socket to get the bolt out of the PTO pulley assy.(electric clutch). If you don't have an impact wrench take a spark plug out and push rope into the hole. This will bind the cylinder and keep the drive shaft from turning. Remove rope and replace plug when finished. Battery and/or spark plug wires should be removed for this process for safety.
The PTO may be stuck on there so you may want to tap it with a hammer and a block of wood carefully to release it. Loosen old belt from tensioner pulley. Lower engine pully on drive shaft, below pully "keys". It may be difficult to remove. Spray with "PB Blaster" or similar bolt loosener spray. Remove old belt from engine pulley first, transmission pulley last. Remember how belt goes around pulleys before doing so, make a diagram to help.

You'll need to put the belt on the transmission pulley first then thread the belt up to the engine pulley. Thread your belt back through the pulleys and tensioner (make sure your spring is strong enough to tension the belt or buy a new one).

The PTO pulley is "keyed" on the shaft. Replace bolt and washer. Torque bolt to 38-50 ft. lbs. using the rope meathod as described before. Put your deck back on and you're ready to mow again

Do the shafts spin and not the pulleys? if so you need to replace the shear pins. If nothing works are there belts that drive fron the PTO could be a broken belt.

The pto maybe bad or bladles bloked or bearings out of spindle

check the deck carefully it might be written on the right side

Most have a bolt on end of crankshaft. Remove bolt.

Sounds like you have defective diode rectifier. this little box when working properly allows your voltage to only go 1 way to charge the battery. if you have used a vehicle to boost the tractor you have damaged the rectifier. because a vehicle running puts out 14.8 volts lawn equipment is 12 volts only you can boost using a vehicle only if it is NOT running

rear pulley has a bolt which allows it to move thus allowing belt to be put on

sounds like a broken shaft in the gearbox!

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Ranch King is a brand name of the manufacturer MTD.

Product manuals with part blow-up diagrams are available from MTD's web site,
http://www.mtdproducts.com/
Models are identified from the model number printed on a label under the mower seat.
The PTO and deck drive belts are shown on one diagram and the transmission drive belt is shown on another. The Form number on my printed Operator's Manual is 770-10526A (22HP, 46in cut) for Hydrostatic 817/818 models.

Parts can be ordered directly from MTD or other distributors on the web.

It is my experience that original brand name MTD belts work best.

The 22HP, 46" mower deck Ranch King Pro has 3 belts:

The drive belt which runs from the engine pulley back to the hydro drive unit to provide over-the-ground propulsion is part #754-0349.

A mower has either an electric PTO or a manual PTO, not both.

The electric PTO belt the provides power to the blade deck (runs around the electric clutch on the engine shaft (activated by electric switch, not the mechanical hand lever that engages the mower deck) is p/n 754-0476 for the 46" deck.

The manual PTO belt the provides power to the blade deck (runs off the pulley on the engine shaft (activated the mechanical hand lever to the left of the steering wheel that engages the mower deck) is p/n 754-0228 for the 46" deck.

The deck belt that goes around the 3 blade spindle assemblies on the mower deck, to drive the grass cutting blades is p/n 754-0349

In my experience, the PTO belt lasts about half a season, the other belts break about every other season when mowing 4 acres weekly.