Final drive issues

[audio2u]

Through this past week, I noticed that the cap in the middle of the final drive housing was missing, and that there was a small quantity of lubricant or oil coming out of the hole.
From back and forth conversations with Alex at Triumph Australia, he sent me this photo explaining that #1 is really just an aesthetic plate, #2 is where the final drive lubricant is added, and #3 is the final drive lubricant drainage hole.
The piece I've lost is #1.
Without having seen the bike, Alex suspects that there is something larger at play here than just the lost cap. His thinking is that if there is oil coming out of that hole, then a seal somewhere has failed, and that could be either somewhere in the final drive itself, or it could be from the engine and has traveled down the drive shaft before finding its way out of that hole.
2 questions....
1. Anyone care to venture a guess as to what the problem might be (or have encountered this fault before)?
2. I've covered the hole with a healthy dose of gaffer tape, just until Triumph get me the replacement part. This prevents any fluid getting out of the hole, and any dirt getting in. But is the bike safe to ride? Or should I stay in a cage until a deeper investigation has been undertaken? Thanks for your input!

[1150newguy]

My 2014 has never had a cap or cover in the #1 area in the center of the rear drive, just the hole like shown in your photo. Are you sure there is something missing there? Mine has always looked just like yours. However, I have no oil residue there either. It is dry as a bone and nothing but some road dirt at this point. Could be you have a seal that is leaking slightly and should be checked out. If it is just a bit of oil and not dripping you may be okay to ride. Remember, a drop of oil will collect a pound of dirt making a small leak look much worse than it is. From what I have read on here Triumph doesn't repair the rear drives, they just replace them.

[1675]

Had mine since new and no "cap" ever been fitted. This is a through hole and a cap would be merely decorative anyway

[DaMonk45]

I would be very doubtful of oil traveling all the way down the drive shaft, through the seals, then up and out.

I would drain it, check for any small bits of metal, check also for how much drained out. Refill it with the correct amount and then check it frequently for a bit.

[towersk]

My '13 looks the same as the picture, no cap in the center.  I don't see a cap shown in the service manual either.  Are you sure that lube is not leftover from a tire change or wheel removal?
The hole in the center of tube does go all the way through.  Check the fluid level and make sure that it's at the bottom of the flier screw hole.

[earthman]

Originally Posted by DaMonk45

I would drain it, check for any small bits of metal, check also for how much drained out. Refill it with the correct amount and then check it frequently for a bit.

Good advice there, going by own experience, mine had too much oil in it, pressure builds up on a long run, forcing a small amount of oil past a seal, well that's my conclusion, since I drained/re filled with the correct amount, all seems to be OK.

[audio2u]

Interesting re: correct levels.
Dealer is ordering a new seal today (should be here tomorrow), so hopefully, when they fit that. they will also ensure the reservoir is filled with the correct quantity of lubricant/oil.

[Coconut]

Interesting 

Other Members have reported previously that there are no replaceable seals in the Final drive Unit,
and have had the complete Unit replaced - I wonder if it's been modified so that this seal IS replaceable ?

EDIT - Aah - I see from your other post discussing the same subject
that it may just be the "O" Ring on the filler plug !