Maybe this is a stupid question but do you have the retract strut turned around the right way? That is to say is the 360 loop is properly absorbing the shock? If the strut is turned 180 degrees opposite of what it should be it will bend badly every time. Im trying to state my question clearly. Ok, how bout this. The spring loop should be closer to the trailing edge of the wing than the vertical shaft that is attached to the retract mechanism and the wheel. If the spring is in front of the shaft (closer to the leading edge) it is backwards, the spring action wont work and it will bend every time..... Just a thought.

All that being said I do have to straighten mine a little after a landing in grass, but I use small foam wheels so I dont bounce on touchdown. I think rubber wheels would help but they are way too heavy so I just hit the runway every chance I get!

Mike