I have a walker mdd and i need to remove the pto gearbox. what is the best way-- it's burried!

I am not familiar with the model but I have some experience with the PTO fitted to truck gearboxes for various purposes. These are fairly crude spur gears and consequently are designed to be engaged only when needed and can be damaged if the vehicle is driven at road speeds with the PTO engaged.
The PTO can be a simple mechanical drive via a propellor shaft or direct to a hydraulic pump, water pump or generator and engagement is a matter of sliding an idler gear into mesh between the gearbox layshaft and the PTO and this is accomplished by manually operated rod or cable, switched vacuum, air pressure or electrical means; motor or solenoid.

It is easier to discover what is wrong if you first discover how it is supposed to work.

That's because the PTO is designed to disengage the rest of the gearbox when the PTO is in use.

A low oil pressure cut out would not prevent cranking. It kills a running engine by disabling spark.

The Walkers require safety states - 1)PTO off and 2)speed control in park/neutral position.

Typical faults that prevent cranking.

1. Operator error... PTO not fully disengaged, transaxle not in neutral.

2. Failed safety switches PTO or neutral.

3. Fuse

4. Loose wire/wire harness.

5. Failed starter switch.

6. Battery

7. Starter/solenoid.

By chance have you had a PTO switch changed ? A lot of the safety switches meet at the pto switch and have to agree for things to work. In your case normal would be you sitting in the seat should allow for engine to start with it in neutral ,blades off and parking brake on.So for you to lift up off the seat and make it work would make me think the logic in the PTO switch is wrong.

Most PTO shafts are a square shaft inside of a square tube to allow for it to go in and out of itself as the mower goes up and down across the ground. You should be able to unhook from the tractor and the gearbox to remove it. In the USA we have farm stores that we go to for the U Joints and halfshafts and connectors to repair them. Some of the parts are also used on trucks so Truck Repair places also. Any parts house can get you a u joint if you bring them the old one to measure.There is also round shaft models but there has to be a slip joint in all of them so no to removing the gearbox off of the mower deck.

The cross feed drive shaft is connected to the cross feed spindle via a coupling that resembles a universal joint that is threaded onto the end of the cross feed spindle. Either one of the roll pin holes in the drive shaft coupling has worn and the roll pin fell out or it has broken, or the coupling could have came un-screwed from the cross feed spindle. Remove the 4 bolts that hold the cross feed gearbox on and slowly pull it away from the machine and you should see the coupling I'm describing. My guess is that the roll pin broke or fell out due to wear. You can buy a new drive shaft and coupling or drill and install the next larger roll pin. Either way you should download a parts list for your machine. Just search for it, they can be downloaded free.

I am a brake lathe technician.

To change the drive belt on an Ammco 4000, you must first remove the 90 degree angle PTO (power take off) gear assembly which is driven off the back of the big pulley. Two small allen head screws hold it tight.

Pull the PTO gear assembly out of the disc-feed gearbox. If there are colored shims between the gearbox and the PTO assembly, you must make sure not to loose. If they drop off, be sure to replace them with a dab of grease.

Rotate the red knob at the back of the machine and the motor assembly will unlock and rotate upwards. Replace the drive belt.

To adjust the drive belt tension properly--loosen the 3/4 inch nut on the back of the machine, and the motor will drop down. Tighten the 3/4 inch nut and then rotate the red knob back until the belt is taught.

Replace the PTO gear assembly--making the rotating part with the protruding pin is centered on the big pulley. Tighten the allen head cap screws.

Turn on the machine. If the PTO is making noise--you have not correctly is correctly. Repeat the centering process until the machine runs without rattling or vibration.

The PTO usually has a clutch that has to be engaged so that you can select the PTO rotation setting. I had a problem like that on my tractor and all it needed was a little adjustment on the PTO clutch lever, so it could disengage the PTO gearbox properly.