I have just received a pair of SE180 motors. In order to access the mounting screws I have to remove the two plastic gears - I can remove the first (upper rotors) gear easily, but how do I remove the second gear (lower rotors)? I don't want to force anything that I'm not supposed to and have something break. Do I need to loosen the outer shaft retaining collar? Because I lossened the screw and it does not move.

I also received a microheli tailboom kit. However I can not install it properly because the M2x10mm cap screw will not screw into the frame as it is a much finer pitched thread than the original screw, and the 2x4x3mm spacer is too long to fit in the space between the boom's mounting bracket and the servo mounting flange. Has anyone else encountered this? It seems so straight forward, I'm not sure how I could be doing anything wrong!

Please help, I would like to get this flying again soon!

Thanks

You are going to need to remove the lower rotor head. Four screws on the outer shaft and the retaining collar screw lose and it will slide out for you. I don't really understand the problem you are having with the boom kit, but let me reread your post and see what the deal is.

I removed everything from the out shaft and took the screw right out from the retaining coller. It still wouldn't move.
After some hammering on the top of the shaft it finally broke free but it was extremely tight in both the retaining coller and the bearing.

I'm not sure how else to describe the problem with the boom - the screw that holds it onto the frame has a different (finer) thread than the original screw and as such, will not screw into the frame. Also, the spacer is about 1mm too long to fit into the space where it is supposed to fit. Is it possible that the newer CX2's have a few slight differences over the older ones?

I can't help with the boom, but I know that when removing the outer shaft, it is tight. When you tighten the bottom screws on the lower rotor head and the set screw on the retainer they leave marks on the shaft which make it very tough to get the shaft removed from the retainer and bearing. I put some light oil on the shaft and tapped on it until it came out. When I reinstalled it I sanded the screw marks with fine sandpaper to help with reassembly.

You can replace the motors without removing the plastic gears (sorry you had to read this after the fact). The outer motor mounting screws can be removed readily. The inner motor mounting screws are trapped by the gears - But you do not have to remove them.... Unscrew them from the motor by picking up the motor as you loosen the screws. Position the new motor over a trapped screw and carefully tighten the screw (avoid cross-threading).

Since you now have the rotor shafts out of your bird, you may find it useful to smooth the screw marks on the outer shaft with crocus cloth before you reassemble things. The newly smoothed shaft will make it easier to reassemble things without excessive use of force.

Cannot comment on tail booms. Bought a carbon tail boom, but never mounted it after reading the stock tail seemed to give better aerodynamics.