Portable HD not showing up

I've been having a problem lately...when I plug my G drive portable HD into my MacBook, (using firewire cord) it won't show up on my MacBook. I take it in and out several times, and sometimes it will, sometimes it won't. Sometimes I just have to let it sit and it'll come up. Now the last couple of days it's really bad, just not coming up. When it's plugged into my MacBook, the light glows on the G Drive, and it makes noises like it's running.

I have no idea if it's the G Drive, the cord, the MacBook, or what??

Any ideas?? Any way to force access to the drive?

Lori