I see your question is a year old, so you probably solved the problem by now. I had the same problem. I bought a container of plumber's putty, and found that it's much easier to use than the strip of putty that came with the fountain pump. To make a long story short, I used about half of the canister of putty....just kept stuffing it all around the cord and and packing the hole. The trick is to use generous amounts of putty. Stuffing it with enough putty finally stopped the leak. For next year, I've bought a big rubber plug. I drilled a hole thrrough the middle of it, and then used a little saw to cut a slit from the side of the plug all the way to the center hole. I'm going to pull the slit open and push the electic cord into the plugs hole...then i'll line the hole where the cord goes through with putty...and jam the plug into it...then push some more putty where the cord goes through the plug. If that doesn't work...I'll go back to my current method, which works fine even though it uses a lot of putty.