I have the same problem with my 300 Special. I had 1 1/2 oz in the right wing to lat. balance, and the plane would snap to the right. I removed the weight started to add weight to left wing just to experiment. It took 2 oz's to take care of the snap on a hard pull-up. The lat. balance is being done by putting a string under the next to the last hinge on the bottom of the vert. fin and holding the crankshaft on the motor. With the right thrust built in is this affecting the lat. balance, or should this be done by finding the centerline of the plane??????