[Al Skierkiewicz]

Phil,
If you cannot find a connection to ground for your breaker panel then you might try a different experiment. If you scope has a three wire power cord, plug it in near where the water enter the house. Then touch the scope probe center pin to the pipe and see what kind of noise you get. If you get no noise, then the electrical system is likely grounded to the water pipe. If the noise is a higher level then at your bench, there may be something wrong with your house. If that is the case and you cannot find a tie in to the water pipe, the cable attachment may have made things worse. I would suspect you have a ground connection but it may be loose or corroded. If you do find the connection, you may want to use an alligator clip to shunt it directly to the pipe and see if things improve.
The power company first response is to say they are not responsible for fixing noise. If it originates in their equipment, it is most definetely their responsibility. I have never had to call the FCC on these matters when I have told them I am looking at their line with a scope. The only way for you to actually look at the line with a scope is through an isolation transformer. Some scopes allow you to display the trigger signal which would give you the same thing. If your scope has a "trigger view" or "view trigger" or "display trigger" function, then select that and then select "line" trigger to see what is coming in the power line.