Mine also has the grease nipple fitted, twice a year I give it about 10 pumps of JCB high pressure waterproof blue grease. It runs as quiet as a whisper at all speeds and loads even down to 2000rpm
The hole in the bell housing is about 1-11/4" dia. This is not critical.
To get a datum measure the centre of the compensator at the top through the steering rack cut out and transfer the measurement to the bottom.
Couple of photos showing a compensator complete with grease nipple packed with grease while being assembled on the bench and a compensator housing showing the cutaway on the top for the steering rack and the hole that was drilled for access to the grease nipple. Hope this helps.
Thanks, already had the compensator replaced. I'm pretty sure it's a chassis type noise. I squeezed some heavy grease into a few likely locations. I'll see if that made any difference. LarryS