Summary

This is a replacement part control stick assembly for my kids cheap micro IR RC helicopter controller(gray in pic). Probably a standard part for RC toys so view the .stl in Meshlab and compare it to your broken part.
I also included the USB charger board enclosure I made when we first got the toy as the included charger burns through AA batteries fast.

Instructions

Open your helicopter controler and remove the broken part, view the .stl to be sure this is compatable, maybe photograph form a few angles first to ease reassembly.
Print this at 10% size with a 10mm brim, you might slow the printing speed as I had problems with the control stick getting melty sloppy, trim the brim and open the holes.
I could see the position of the spring on the other control stick.
.scad file attached so you can edit in openscad.

The USB charger enclosure is also printed at 10% size it has a hole for a LED on the board I have. I found some electronic cigarette chargers for $0.50 each, they are standard 3.7v lithium chargers 400mA, 3.7v lithium battery charge controllers are also available for a few $ on auction sites. The charger cable is a modified 2mm Nokia type tip with the plastic trimmed back so it inserts far enough, verify polarity by plugging into the toy and testing the polarity of the electrical backflow with a multimeter. There is room for a cable strain relief on both sides, I just edited the stress relief holes totheright size and hot-glued them in, once all parts are fully cooled down the lid snaps in, I hot-glued that down too once I saw that it worked well. I made a USB charger as this toy would burn through the 6 AA batteries in less than two hours of play using the charger cable built into the controller.

Repair Micro RC Helicopter Control Stick and USB Charger