When I had the Roadster there was a similar issue.
The upper and lower plastic covers were rubbing on the steering wheel boss.
I increased the size of the aperture in the covers for the column and that helped, a lot.
There is a UJ in the column along side the engine. That also required lubricating.
But the problem was solved with hard chrome "king pins" and the SSL suspension upgrade.
The varying friction can be due to the lower springs rubbing as the steering moves. With the SSL upgrade the lower spring doesn't touch the suspension unless the car is under downward load.
Anyway, the car ended up with no "nodd", much lighter steering load and no friction, anywhere.
