To paraphrase 3D, a nose-heavy plane flies poorly, a tail-heavy plane flies once.

It might do you good to use an airplane balance jig instead of your fingertips. I used to use the 'fingertip' method (put your fingertips where you think that CG is supposed to be) but was much happier using the balancing jig.

You can make one using a piece of pine for the base, and a couple of 8" pieces of 1/4" aluminum rod. Drill a hole in the base for the rods (use a drill press if you can, so that the rods are nice and vertical). Space the rods about 6" apart. Round over the tops of the rods where they will contact the airplane(remove any burrs so that you don't damage the covering). Make sure that the tops of the rod are even, so that your plane will sit evenly on them.

On your plane, measure carefully and put some masking tape marks on the wing where the balance range is supposed to be. Rest the plane on the balancer so that the rod tips are on the masking tape (within the range) and balance it (with the empty tank, as mentioned previously by Daveo). Make sure that there is balsa sheeting where the balance range is supposed to be. You don't want to rest the plane on just the covering - it might poke a hole through the covering.

That jig only cost a couple of bucks to make, and has been a real nice addition to the tool shop. I've re-checked planes that I initially balanced with the 'fingertip method' and found that I still had to add weight here or there to bring the plane into balance. And the difference in flying was better too.

Just my $.02. Hope this helps,

Bob