fuel gauge intermittently not working

I have a 97 Grand Prix GT and the fuel gauge is intermittent. Most of the time it pegs to full, and then once in awhile it will read accurately.

I've read two suggestions in previous posts here:

1. That it is the fuel sending unit, which is hooked to the fuel pump (all as one unit).

2. That it is the instrument cluster.

Does anybody have any knowledgable advice to which is most likely? I find it hard to believe it could be the instrument cluster, but someone said they replaced theirs and it worked.

Thanks!!!

Well I got ambitious yesterday evening and I believe I found the problem. If anybody else has had this problem, you might check into this...

I took the fuel pump out (which is super easy to get to now - thanks GM!) You can access the fuel pump through the trunk - right behind the rear seat. Just take the metal cover off and vwa-la - instant access to fuel pump.

The problem was that the two metal contacts that touch the float switch pad were not completely touching anymore. So I was able to disassemble that section of the unit and bend those contacts to where they touched the switch pad.

Took me about 2 hours to figure everything out and do the work.

If I took it in to a dealer or whoever, they probably would have just told me I needed a new fuel pump...and I probably would have walked away with a $400-$500 bill.