MrWillys I completely understand about the leaks!
The last thing I want to do is create a negative impression on the gears, but it is what it is, ultimately I also thought that there could have been an adapter issue, but its a brand new AA unit with brand new bearings, plus with the stock gears the noise is much much less so I guess I've just hit bad luck in this regard.
Admittedly the Tera gears look like a work of art, very well machined, and despite the noise I could not see any noticeable points of wear or possible contact points due to misalignment. The Tera team told me to run the gears in for a few thousand miles to see if the noise reduces in some or other way. Problem is this is not my daily drive, a few thousand miles will take me 5 years! I've had varying comments locally about the wearing in bit, not really sure if it will work.