Blinker problem!

I have a 79 kz650.

My right turn signal works fine. My left, however, goes dark in the front and solid in the back, but the marker lights are on fine with no blinker. I'm wondering what I should look too for troubleshooting this. I'm not so great with electrical, but I'm learning. I have a multimeter to help test.

Thanks for your help!

You need the bulbs to be good and correct, good contact in the sockets. The Flasher relay requires the Load from the bulbs to work. So if the Marker light works, but the turn doesn't on any socket, start with that location. Pull the lens and check the bulb, and socket for both a good set of filaments and any corrosion.
Then you could have an issue where the connectors plug in, or possibly a bad or missing ground at that socket. "File Base" at the top right corner of the page, should have a wiring diagram for your bike. Remember it takes both the wiring bring voltage from the power circuit and a ground to operate.