It is quite possible that it needs this much weight.

Before adding any weight, move the receiver and battery as far to the rear as possible (use a 6" HEAVY DUTY extension for the battery if needed ). You may also want to consider going to a larger battery (1800 - 2200 mah ). My personal feeling is that if I have to add weight, I try to make as much of as possible "useable weight".

To secure the battery, use industrial strength self adhesive velcro. Wrap the foam around the battery with some masking tape and attach 2 strips of the velcro to the masking tape. Next, remove the velco from the part attached to the battery and LIGHTLY readhere the 2 pieces. Peel the backing off the other half and lightly press in place. Now, using a flat blade screw driver, hold the part attached to the fuselage down while you remove the battery.

Next, press the velcro against the fuselage firmly and wick some thin CA between the velcro strip and the wood in the fuselage. (the adhesive when used against wood, tends to loose its grip in a short time. The CA insures it stays put.) When the CA is dry, press the battery in place on the velcro strips. (The battery WILL stay put even through hard crashes ).

Now rebalance the plane. If you positioned the battery correctly, you should need little, if any, additional weight.