Wrong assumption, the unipivot is soldAssuming this was a pivot arm, it's likely that the test tracks are in different locations on the 33 vs 45 LPs. A different relative location from the null point is likely to exhibit different crosstalk characteristics. Also the rotational speed difference technically should be compensated for with different anti-skate settings (which obviously nobody does). This will affect observed crosstalk however. Lastly, the LPs themselves could have small differences as you noted. Nevertheless, I'd contend that Analog Majik is doing its job.
it’s the gimbal VPI 12” Tonearm. The differences are between two different 33.33 pressings of AM not between the 33.33 and 45 rpm pressings.