The other side of the pond is where all the ‘secrets’ are.
And how do the bearings get lubricated?
If you have done maintenance to the KZ you will find that the some of the GB bearings are sealed, some are not. The gear box shafts turn at approximately 3500 rpm. The bearings will hold up fine without lube.
My son tells me I provided a KZ for a couple of races a few years back. No oil in gearbox. Never found out until I took engine down.