Fixing Broken Shimano Indexed Tourney Shifters!

In this Instructable I'm going to show you how i dissasembled, fixed and then reassembled my Shimano Tourney ST-TX800-L lever. This might work on similar indexed shifters too.

Supplies

A 5.5mm socket and ratchet/screwdriver (For my particular shifter, it might be different on yours if it's not the same exact model)
Super glue / a cyanoacrylate based adhesive. (Something else might work too, this is just what I used and with good results)
Some grease maybe but I'm not even sure if it's necessary

Step 1: Step 1: Symptoms & the Culprit

I first noticed my shifter was broken when i tried to shift into a larger front ring by pushing the lever and it didn't do anything. The problem was that two of these tiny plastic parts had split into two pieces each. In the two pictures you can see one of the broken parts, before and after being glued back up.

To fix this I:

cleaned them with soap and water in a bowl (I would advise against doing it in a sink because the parts are tiny and might slip and fall down the drain)
Super glued each plastic part with it's split piece.
Found out the root cause of the issue which was a kink in one of my shifter cables causing it to be wayy too hard to pull. I solved that by straightening it with two sets of pliers and then greasing the cable up, however, the ideal solution would be to replace the whole cable.
Reassembling the shifter

Step 2: Step 2: Dissasembly to Find These Broken Parts

To disassemble the lower part of the shifter:

Remove a tiny plastic cover that can be popped off with a flathead screwdriver/ random knife tip.
Unscrew the nut holding the lower part together.
Kinda twist and turn the lower shift lever until it comes apart
Remove a cap
Remove a torsion spring
Pull up the whole lower lever assembly, revealing the yellow plastic parts mentioned in the previous step, the lever itself and a lockring of sorts
Inspect the yellowish parts to find whether any of them are broken/split up.

Also here's a video of me dissasembling it

Step 3: Step 3: Glue the Broken Yellow Things and Get Everything Ready for Reassembly

In the picture you should be able to see how the lower shifter should look like before being re-inserted.

Things to note:

There's a hole for each yellow part to go into, where they can pivot
The lock ring holds them up by that little lip they have on the top
The lock ring is not a full circle, and it has a hole which matches with a solid part of the lever (pointed at by the red arrow)
When pushing the lever into place, push the shifter from the top side to make the screw in the middle stand out (i didn't do it during the video and that's why i found it so hard to close everything up).

Step 4: Step 4: Reassembly

Slide the lever and ball thingy back into place, and put on the torsion spring and cap then squeeze everything together and lock it all up with the nut.

Personally, I couldn't get it to close with the torsion spring in place so i just assembled it without it and it works fine haha

Step 5: Step 5: Conclusions and How to Avoid the Shifter Breaking Again

So after all of this your shifter should be back working but after this I've learned a few things.

Check your cables for any kinks or rusted spots, and grease them up/straighten them or just replace them to avoid placing unneeded stress on your shifters
Do not under any circumstances try to shift your front gears then you're not pedaling the bike forwards

Reassembling the shifter with the torsion spring in place was way too hard so I just left it out. Shifter functionality is not affected, you just have to pull back the lever after you push it manually but it works perfectly. If you can manage to reassemble this thing with the torsion spring and all you really have way more patience than I do haha