The picture I’m getting is there is no hum until the stylus sets down with enough pressure to move the cantilever and that’s when the hum starts. If so not good, as it probably indicates a fault inside the cartridge itself.
Simple test, watch closely as you slowly lower it down onto the Onzow. If the hum starts the instant it touches the surface then its static or electrical or at any rate something outside and you can deal with it. If the hum only starts after the cartidge is lowered enough for the cantilever angle to start changing though then it seems to me its probably inside the cartridge.
Try the same test on a stationary record, and on the NON moving platter, and on a playing record. Lower it real slow and watch real close to see exactly when the hum starts.
Not sure how experienced you are but there's a normal range the cantilever angle goes through moving up and down. If it goes too high or too low outside that range the same happens at the other end, where there's coils and magnets crammed real close together, just begging for trouble if that happens. Could be one time it got caught on the cleaner or something tweaked it too far and now you got problems. Just a guess at this point.
