Demagnatize cartridge??

I doubt that the 304 was magnetized by the stylus gauge. Every MC, MM, or MI cartridge contains powerful magnets to enable it to generate a voltage when the stylus moves. It sounds like your stylus gauge is attracted to the cartridge's magnets (and MC cartridges have the strongest magnets of all).

I'd get rid of the gauge - I think it should be made of non-magnetic materials.

As for the hum, I don't see a connection. Low output MC cartridges like the 304 need a lot of gain. It's very easy to pick up hum with high gain.

IS the turntable ground wire properly attached to your phono front end? Are you sure the headshell wires are properly and firmly attached to the cartridge (my 304 seems to have small diameter pins - I had to squeeze the clips a bit to make them work)?

What kind of phono front end are you using?

BTW, I think the 304 is a great sounding cartridge. I'm running mine at 300 ohms right now, but am still experimenting.

Cekiv - I have my 304 mounted on an overhauled Yamaha PX-2. The cartridge came with 2 sets of screws, one pair too short and the other too long. I used the too-long screws of course.

I had no problem balancing the cartridge and setting tracking force to 1.2 grams, though the cartridge semed pretty light compared to the Shure Ultra 500 I had mounted previously. The balance weight is pretty far forward but not at the end of its travel, which is a good thing.

Surprisingly it tracks very well. I wasn't sure what to expect with the Denon - the Ultra 500 is a tracking champ.

As I mentioned, the headshell clips were loose on the cartridge pins. Did you notice this? A good bump could dislodge a connection if you didn't crimp the connectors for a snug fit.

My phono preamp is a Pass X-ONO which is dead quiet with this cartridge even though it's set to maximum gain.

Did the hum start after the collision with the scale? Does it occur in both channels or just one? When you mounted the cartridge, did you do anything to prevent electrical contact between the cartridge body and the headshell?

BTW, I recently bought the cartridge new from ebay from a German dealer (I'm in US). It came within a week of purchase in unopened condition - no problems. He had a few more in stock if anybody else wants one.