Uneven VTF on different part of same LP

Yes, to both!

Dear Doug,
First thing crossed in my mind was that my tonearm is already about 10 years old, and aside from replacing the cartridge or checking its setup about every 4 months or so, I almost did nothing (maintenance) to my tonearm, hence my qustions were mostly related to bearing :)

Thanks again for the advance, indeed I still need to learn new things about turntable set up after more than 10 years playing around with it.

Gondo,

Your tonearm's bearings don't require any maintenance. Every year or so you might do a gentle zap of compressed air (from several inches away) to remove dust and the odd cat hair, nothing more.

Any decently made tonearm, including yours, should last far longer than 10 years without significant degradation of the bearings. The stresses imposed by typical usage are far below the damage threshhold of the materials most tonearm bearings are made of (hardened steel, in your case). I have a 35 year old tonearm, less well made than yours, that has no detectible bearing damage or wear.

For the bearings to be damaged enough to cause .04g of VTF change would be highly unusual, and could only happen if subjected to some form of user error or abuse.

Of course damage or contamination could occur from rough handling, a dirty environment or heavy use while mis-adjusted. But assuming such abuses did not occur, bearing damage was the least likely cause. That's why I listed it last.