Phono Plugs

I'm having a problem with the plugs on the phono cable on my Nottingham Interspace arm. When removing the plugs from the preamp the center pin stays in and the outer shell pulls off -- requiring that I then tug on the actual wire holding in the pin to get it out. The plugs screw apart and I've had to take them apart several times to make them work agian. But I'm not getting them together properly -- I'm getting hum through the system -- which I can stop by manipulating the cables -- not a good idea I know. There seems to be no alternative but to replace the plugs -- and here's where I need help. I'm not quite sure how to do it -- I've noticed inside each plug is a bare wire -- I'm assuming this is the ground -- but it's not clear to me how that fits into the plug as a whole -- what it is or is not supposed to touch, etc. Does anyone know of an internet site I might be able to access for help? Any special plugs I should use to replace the current plugs? Or any thoughts comments on what I should do? Thanks in advance for all of your help. (Sorry this was so long and so imprecise).