With the blanking plug, just make sure you're using a good quality, correct size allen key. Make sure it's inserted properly, plenty of leaverage and it will eventually 'crack' open probably taking all of the skin off of your knuckles lol. Once mine was cracked it just screwed out with my fingers, no problem. Once you've got it out save the copper washer and put it onto your sender (or better still get a new one), it's the washer that creates the seal so you should'nt need any thread tape. Sound simple but it's easy to damage and once it's rounded off you're really going to struggle.