My turn signal was starting to act up, not signaling left unless I monkeyed with it. Time to clean.
I thought I would post this, to help anyone who is having the same problem.
It's easy to do and only takes a few minutes.
My bike is a 2000 ACE T, I assume most other Honda switches are similar.
I removed the 2 screws that hold the switch housing together. Carefully pull the 2 halves apart. I did not remove it from the handle bar, and did not disconnect anything. Just let it hang.
Use electrical contact cleaner. I wish I had not lost the little plastic spray tube, but I did fine without it. Do not use anything else (brake cleaner, carb cleaner, etc), as some cleaners will attack plastic parts.
The contacts are hard to see, I marked one of them (I am holding turn signal in the right direction, so you can see the back side of the left contact). The front contacts are on a plastic slider, and you can not see them.
I chose to not disassemble any further, as I didn't think it was necessary.
I sprayed the cleaner liberally inside the switch. Clean everywhere you can with Q Tips. Spray while moving turn signal switch left and right, back and forth. After it's all cleaned up, give a few minutes to dry out.
I applied lube to the slider only, where I have it marked in the photo. I don't know what the correct lube to use is, but I used Militec-1 grease. It is designed for military firearms, and is good at all extreme temps. I applied only a tiny amount, with a toothpick.
Reassemble, and my turn signals work fine now. While at it, work your hi/low beam and horn switches, and blast them out too.