Bearing lube for Dynavector tonearm

I own a Dynavector DV505 that has been idle for many years. I now want to install it, and I noticed that there may be a bit more friction in the horizontal bearing than I am used to, compared to my other DV505 that is in constant use. There is absolutely no rubbing sound or real resistance to rotation about the bearing axis, but just a tad less sense of freedom of movement. Does anyone know about lubricating the DV tonearm bearings? Is it periodically recommended or are these sealed bearings that should be left alone? If it should be done, what lubricant is favored? I put this question to the US distributor, and he is trying to find out from Dynavector Japan, but I thought I would bring it up on this forum. Thx.