Welcome to this tutorial on how to fix that irritating side indicator that tends to get stuck on amber when trying to signal. The fix is relatively easy and should take you less than an hour to fix. I have successfully fix this issue on my 1973 Toyota Celica, but I assume most Toyotas of the same era use the same system.
Step 1 - Locate the Relay
The culprit of the sticky indicators is the mechanical relay which is situated under the dash, where the steering wheel, offset above the accelerator pedal. My relay had a brown backing with a goldish metal cap. By time or lack of use the arm inside the relay that oscillates gets jammed and all that has to be done is to loosen it a bit for it to freely move again.
Step 2 - Disassemble the Relay
Using a thin flat screwdriver, lift the 6 metal tabsand pull out the relay from its casing.
Step 3 - Loosen the arm
Check for any debris or dirt and clear it out with compressed air, additionally use any electric contact cleaner as a good precaution. At this point you would want to re-install the relay into your car to see if the issue has fixed itself and if not go further and analyze where the arm is getting stuck and adjust the contacts accordingly.