Another complication. Putting the anti-skate back on didn't solve the problem, so I contacted Tri Mai at Triplanar who was very helpful. I had this problem years ago, but thought it was solved. Apparently, when I removed the arm to remove the damping trough, the wires running from the bottom tube on the tonearm were pulled slightly tight, putting tension on the arm and causing pulling and vibration, especially when the arm neared the center of the record. Tri suggested pulling the wires slightly loose thereby relieving the tension and allowing the wires to float as free as possible. My first attempt caused things to be much worse, and subsequent attempts improved things but were not perfect, and the wires seem to quickly slip. I had an upgrade somewhere between 5 and 10 years back, but apparently this was not fixed with that upgrade. Before spending another nearly $1500 for another upgrade, I wanted to find if anyone had dealt with this before successfully and how. Also, does the most recent upgrade completely solve this, and if so, how? I initially thought much of my problems were in the cartridge, but this made me realize that it may be more the tonearm, as slight changes make HUGE differences.