Where can I find the little piece of plastic that goes on the turn signal switch? 

That's a rather vague description, but I'd take a punt that you mean the grey blanking plug for the lights on/off switch?

If you're in the US, then I think that DEET here on the forum has some.

I am in the UK and used Kawasaki part number 46089-009. I wouldn't go so far as to say that it is identical, but it's jolly close. I do have spares for those in the UK that might be in need of one.

Or did you mean the plastic part on the lever? The attached is a later version.

YAMAHA HANDLEBAR SWITCH REPAIR KIT TURN SIGNAL/WINKER KNOB KIT INDICATOR KNOB | eBay

Yes that's it Thx. Winker knob kit. Trying to find one in the US

Let me know if you find one in the US, I am looking for the same thing.......   (just the knob, not the entire lever if possible)

Have a look at Kawasaki part number 46044-010. There are quite a few on fleabay and they aren't expensive.

The complete Kawasaki switch housing that I referenced for my grey blanking plug is a close (but not identical) match to the Yamaha part - it is made by the same company. It then seemed logical to me to check out this complete unit for other individual components and hence the part number that I have quoted here.

Unfortunately (for me!) I don't think that the inner light toggles are quite the same as Yamaha's, although I haven't tried one out yet.

The vintage spoke has them USA  



 

$12.70. Will not let me attach a pic

Thanks GR8,   for $6, I will try it and see if it works. 

The Kawasaki part number worked great...... Thanks for the advice GR8