Ouch! Sorry for your cartridge. :-(
Here's an old trick for tightening cartridge clips safely. Stick a round wooden toothpick inside the clip. Squeeze *gently* with a hemostat, strong tweezers or a jeweller's needlenose pliers. The toothpick "gives" enough to let you compress the clips without flattening them out, and you're not working on the cartridge so no risk of damaging that.
No better ideas on grounding than what Bigtee offered, except to make sure the Nait itself is grounded and that the ground it's plugged into is good. You need a ground tester for that.
Here's an old trick for tightening cartridge clips safely. Stick a round wooden toothpick inside the clip. Squeeze *gently* with a hemostat, strong tweezers or a jeweller's needlenose pliers. The toothpick "gives" enough to let you compress the clips without flattening them out, and you're not working on the cartridge so no risk of damaging that.
No better ideas on grounding than what Bigtee offered, except to make sure the Nait itself is grounded and that the ground it's plugged into is good. You need a ground tester for that.