The Align servo control rod upgrade kit is a small pack of control rods with ball links to allow the Trex to get rid of the z-bend linkages on the servo control horns and use proper ball links instead. The kit contains four pushrods and associated purple colured ball links (the new better fitting ones). The upgrade kit assumes that you already have the purple links on your machine as there is only enough puple links to replace the z-bends. If, however, you have purchased the linkage upgrade kit, also covered here, there are the required ball links in this kit to do the full conversion to purple ball links on every control connection. The kit contents for both upgrades are below, the servo control rod kit on the left and the linkages kit on the right.
	Fitting the servo control rod upgrade is a simple affair, you remove the z-bend control rods and simply replace with the new control rod with ball links on both ends. The original z-bend can be used as a comparison to make sure you get the control rod lengths correct. Seen below are the control rod package contents and the control rods ready for fitting. In this picture you can see the lack of replacement purple links for the original grey ones.
	The pictures below show the new control rods fitted.
	The next task was to do the control linkage upgrade, this changes all of the remaining grey links for the new, slop free purple links. For the most part this is just a simple case of swapping link for link and keeping the lengths of the original rods intact so as to not upset your nicely trimmed out heli. Unfortunately, it isn't as simple as it looks The upgrade kit contains replacement collective pitch/elevator arms for the elevator/collective pitch seesaw, pictured below left. These triangular arms fit onto the lower swashplate and are located between the side frames next to the main rotor shaft. Removing these proved to very difficult and at one point I thought I may have to take the mainframe apart. However, it is possible to push out the pin holding the triangular arm by just loosening the four screws around the main shaft bearings. Pictured below right and highlighted in red. This gives just enough room to work and get the retaining pin out, although it was slow and frustrating work.
	The last pictures here show the new upgraded linkages, including the main servo horn ball links (purple ones), which are included in this second kit.
	So, the question is whether all this actually makes any difference. Well firstly, before I started the entire control system felt sloppy and loose, there was lots of movement in the head, swash plate and mixers. Post upgrade the entire head is extremely tight and almost slop free. Some of the purple ball links are a little tight, a good tip to free them up is to put a small (circuit board type) soldering iron on the metal ball of the ball link, then rotate the purple link gently, this smoothes and frees up the movement nicely, just don't over do the heat. My verdict is that this is a very worthwhile upgrade as the slop in the head control linkages is now virtually gone.