I'm slowly putting together my 450XL HDE. I got the head onto the frame today along with the main gear. (with Finless' video's help) After tightening things down, I noticed the main tail gear underneath the main gear is deformed. The gear is not uniform where the whole gear is in the same plane. I can see it "move" up and down where it contacts the tail drive gear assembly. I think it's caused by the screw at the bottom of the gear holding the main shaft. What can I do the resolve this? The only way to keep it somewhat uniform is to loosen the bottom screw until the shape returns. But I'm afraid it will work itself loose easily that way. Have you guys had this problem before? How do you resolve it?

Use a small touch of thread lock on the screw and don't tighten it to the point where you distort the gear. Don't overdo the threadlock as the nut sits in a hex recess that you can't get a spanner or pliers into.

Personaly I find that the friction between the screw and the plastic gear is enough to stop it coming loose.

Thanks for that tip. I was able to get the gear and the sleeve back in shape. So although still warped a little, it's not rubbing on anything now. I will just trust the friction and threadlock.

Most Align gears do not run true, but they generally work fine.

Thanks for the help. I flew it anyways, and it looks like it will be fine. The pilot(me) however, is a different story. After getting too close to a pole, I moved the stick too much. (bad habit from a df4) The TRex's blades were perpendicular to the ground, and I couldn't recover in time. Broken blades, paddle, head, washout, seesaw.