I think you need to correct the nose heavy condition since it could contribute to your problem.

Mine was so nose heavy I had to move the 9.6 volt ECU pack under the center fuel tank. The two radio battereies (6.0 volt) were moved to just forward of the fuel cells. With this done the airplane balances perfectly. All the packs were made using 1900 mah cells so the batteries are quite heavy.

The only thing I have in the nose battery holder are two air tanks - no batteries.

Hope this helps.

Jack Mathias
AMA 7654