G'day winsurfr.
May I take this opportunity to Welcome you to the forum and I am sure you will find all the help and advice you need to keep the old 65 Working.
You mention you have a manual ,if you study it you will see that the tractor has Reduction hubs / Epicycle units taking the drive from, the gearbox to the rear axles along the way passing through the inboard disc brake units.
Firstly may I say that it is most important that any wedge/ block etc that is placed between the front axle and the axle housing is REMOVED before you move the tractor otherwise there is a real possibility that you could crack the cast iron axle housing especially if you were to travel over uneven ground.
The brakes:
The brakes on the 65 are originally Dry discs and on the whole are reliable and work very well ,but like most things mechanical they wear out to the point where they need attention ,as in your case oil leaks and contamination .
The job you are about to do is indeed I suppose like most Mechanical type work involving heavy items potentially dangerous and so long as you approach the job with a specific task in mind and the task is broken down into easy uncomplicated operations ,the risk will be minimised .
before you start you need to, KEEP ANYONE NOT INVOLVED WELL AWAY, Especially Children.
Have the use of a hydraulic floor jack ,a Concrete floor to work from will also help and a chain block or something to help when removing replacing the rear assembly.
You will be replacing seals and most likely bearings so the first thing you should be aware of is $$$$$ it is going to cost a bit of money which ever way you go.
First step is to secure the tractor chock both the front wheels and the front axle pivot point note before driving in wedges make sure the tractor is as Level as possible this will make the job easier .
Remove the mudguard and any wiring,remove the brake rod,Completly.
Jack the rear of the tractor up ,under the drawbar frame and slightly towards the side you are removing, if the tractor has cast wheel centres you are dealing with something that could weigh around 500/700 kilograms either wrap a suitable sling THROUGH the wheel assembly and lift of with chainblock or other suitable lifting gear or Walk the wheel off being carefull to keep it as upright as possible.
Drain all oil from the transmission and rear compartment ,Two drain plugs.
Support the rear end of the tractor using a suitable stand , undo all bolts holding the rear axle ASSEMBLY to the transmission housing leaving two at the top to hold everything together , use a chainblock or other lifting device that is controllable bearing in mind you do not want to damage threads on studs etc put an oil drip tray underneath the join as you will get a wee bit of oil leaking out when you remove the assembly, when rigged up and ready to lift off undo the remaining bolts and remove the complete unit .
Once removed Stand it up on end that is with the reduction unit /wheel end sitting on a nice big wooden board .
Remove the two countersunk head screws that hold the inner brake disc friction plate on ,lift the plate of and you can see everything inside .
undo and remove the brake adjusting nut, make sure you use plenty of penetrene otherwise you will snap the adjusting link.
undo the cast brake pivot housing two bolts and remove.
Remove the brake expander unit and discard, In my years of repairing Masseys I have found that It is less expensive to buy a kit which gives you ,two expanders and four new brake discs, this will guarantee that the brakes will operate 100 %.
Mark all parts of the reduction unit with a punch or ??? this will ensure everything goes back the same way undo and remove all bolts holding the assembly together and lift of the trumpet housing.
Remove the drive axle.
You are now into the epicycle, lift of the drive ring
which will be marked then the hub with the gearset you are then left with the wheel/ hub carrier everything is held together with a large thick Circlip, remove the circlip and either press the stub shaft out or bump it apart on a block of wood, Clean,inspect and replace all necessary parts .
to reassemble and preload the epicycle you will have to reassemble and measure the grove width and buy the appropriate Circlip to give you the required end float more often than not you will find that if you replace both tapered roller bearings the endfloat will be within tolerance with the existing Circlip.
There are a few little things you will need to know that are not in the manual which we can talk about as you go .
Happy days .
again Welcome.
Hutch