Iceman:

I love my RCX planes, have had them almost a year and fly them allmost exclusively regardless of the quality of the birds on the ceiling.I perfer the 330L for most work. Sorry to tell you this, but the problem is in the thumb, not the airplane! Suggest you tighten the springs on your transmitter sticks to as tight as you can get them, will help you keep the down and up directions linear. This is somethilng I noticed a while back as a new problem in my flying as age creaps up on the body. The spring thing reminds the thumb to work streight. Something like learning to use the rudder correctly flying 3-d. Something I did not have down pat after 30-40 years of flying normal airplanes. The first few months with the 3-d birds was a tough learning curve for a old guy, but now worth the time and effort. ENJOY