As Dano says the grub screws only poke out a little way so unless the mullered ones are directly opposite each other I'd be tempted to pull that "little bit" harder. I recall that my cap mount was stuck in the tank quite firmly when I first changed my fuel filter and required a fair bit of leverage on it to get it out...
Saying that you're the only one who knows how stuck it actually is and if you stick a crowbar on it and do the tank completely then it was Dan's idea.....
Darren