Inner groove distortion is a not uncommon problem, which can have many causes. Two questions:
1)Is tracking force set too low? If you are not already doing so, set it at or near the upper limit of the range recommended by the cartridge manufacturer.
2)I couldn't find a manual for the RB301, but I note that the manual for the RB300, which I presume is somewhat similar, indicates that anti-skating should be set to be numerically equal to the tracking force. That seems to be a common recommendation among various tonearms and turntables, but it is completely ridiculous IMO/IME, and the experience of many others.
While the stylus is in the groove of a ROTATING record take a look at the cartridge from the front. If you have set anti-skating per those instructions in the manual you will probably see that the cantilever is deflected significantly to the left (toward the center of the record), relative to the approximately straight-ahead position it assumes when lifted off of the record. If that is what you see, reduce anti-skating until the cantilever has no perceivable deflection to the left or right, relative to its position when the stylus is lifted off of the record. Based on my experience with other arms, that will probably occur with anti-skating set to be numerically equal about 50% to 60% of the tracking force.
The technique I use to accomplish that as accurately as possible is to adjust anti-skating until deflection just begins to be perceivable in each direction, and to then set it to the mid-point between those two values. I then verify that no perceivable left or right deflection occurs when the stylus is at a number of different points on the rotating record.
Hope that helps. Regards,
-- Al
