You said you've set VTF to .1g over the level recommended by VPI. That doesn't make sense to me. VTF ranges are specified by the cartridge maker for each particular cartridge, not by the TT or arm maker. They have no idea what cartridge you might use.
Check Grado's VTF spec for the Sonata and try something near or at the top of the range. It wouldn't hurt to double check all your setup parameters, but that's where I'd start.
It's conceiveable you have a resonance problem that's only excited by certain passages on a few records. The best way to check that is with the resonance tests on the HFNRR test record. If your resonances are higher than 15Hz or so then you might (rarely) experience the problem you describe. If that's the case you'll need to add some weight to the headshell to bring resonace freq's to < 15Hz.
In any case, I wouldn't play any records until I solved the problem. Even if the cartridge is staying in the groove there's a good chance that it's mistracking enough to damage your vinyl.
Check Grado's VTF spec for the Sonata and try something near or at the top of the range. It wouldn't hurt to double check all your setup parameters, but that's where I'd start.
It's conceiveable you have a resonance problem that's only excited by certain passages on a few records. The best way to check that is with the resonance tests on the HFNRR test record. If your resonances are higher than 15Hz or so then you might (rarely) experience the problem you describe. If that's the case you'll need to add some weight to the headshell to bring resonace freq's to < 15Hz.
In any case, I wouldn't play any records until I solved the problem. Even if the cartridge is staying in the groove there's a good chance that it's mistracking enough to damage your vinyl.