Having read through this thread in detail I am interested in the outcome.
From my experience a bell housing should not be sealed tight. If it is then as the air inside warms it will expand and have to go somewhere, usually through the oil seals. Then when it cools it will have a lower pressure inside that will stabilise by drawing oil through the seals into the housing.
The belhousing plug should not be installed. It should only be supplied to be installed before wading and then removed after wading.
It is out of warrenty.
Here is a little tale of mine from my experience of Harley Davidson.
In 2001 I bought a new HD Night Train and it cost me 」14500 in inheritance cash. As a novice biker I was unaware the bike was a pile of kak.
The first, second and third sevices at the dealer showed up nothing. The forth service came just prior to the 2 year warrenty expiring but the dealer stopped dealing. I eventually found another dealer willing to take on the service but the available appointment was two days out of warrenty.
The dealer said the bike was dangerous on the road and found that the electronic ignition was shot, the headstock bearings were non existant, the exhaust was incomplete and the engine was bad. They asked me, how long has it been that way?
Ever since I took delivery, and at that point the front tyre was 5psi, the back tyre was 10psi, the gearbox was leaking oil and the hand grips were loose. The first dealer fixed those but the bike was just my first bike and so I had no comparison for how it felt. I was a novice biker, the first dealer knew that.
With investigation the dealer agreed that the bike was a dud and tried to get, at least, the parts covered under the warrenty. No joy, Harley Davidson were not interested and refused outright as it was two day out.
I had to pay for all the repairs and then the bike was a great ride! Powerful, smooth, fun and I could get around corners, with my knee down, without kaking myself. Everything the bike should be.
I tried to get support form the UK owners club about the condition of the bike. They refused to talk to me but kept sending me pin badges. I tried, in writing, to Harley Davison's HO in the US and they wouldn't talk to me either, they just kept sending me the UK club details and pin badges!
In the end I sold the bike and swore never to buy a Harley again and I tell this story to all that ever express an interest in one.
What has this got to do with the OP's tractor story?
The tractor is out of warrenty, by a long way.
The 'customer' deserves Harley Davidson's customer service.
I wish I had the OP's customer service, I'd still be riding a Harley if I had.