Fuel Pump Failure

Hi Folks, would really appreciate some advice please. The fuel pump on my 03 1000Sie is not priming when I turn on the ignition. I've drained most of the fuel out of the tank, removed the cap head and grub screws from the tank ring but it will not budge. Is it just a very tight fit into the tank, or am I missing something somewhere ?
I'm guessing it will be a wiring failure in the tank based on what I've read on here, but I'll know better when I can see the pump and it's associated gubbins.