International 434 brakes sticking on.

[Tonym]

The right hand brake on my ploughing tractor (International 434) sticks on and the only way to release it is to reverse. On removing the brake housing the problem is obvious as there was about half a cup full of oil collected in the housing.
The oil is coming along the diff lock shaft which runs down the centre of the brake shaft. There is an oil seal on the housing which prevents the oil from leaking from the housing but does not prevent the oil leaking internally. There appear to be no more seals so how can I fix the problem.
The only bodge I can think of is to drill a drain hole in the bottom of housing to let the oil out and maybe remove the centre seal so that the oil can get out before the disc is immersed and flings it everywhere. It is only a very small leak as I have never seen oil under the tractor in that location and if it were not for the brake problem I would not bother with it.

Any ideas?

 

[deere66]

There is a seal on the shaft inboard of the brake and another seal and 2 o rings on the diff lock shaft
https://partstore.caseih.com/us/parts-search.html#epc::mr62748ar489174
https://partstore.caseih.com/us/parts-search.html#epc::mr62748ar489608