1982 Westy

The left burner on my range is producing a yellow, inconsistent flame.  When
I remove the burner plate (which splits the gas flow), and light it, the
flame is entirely different and less than the one on the right.

Is it dirty or clogged?  An air mixture issue?  I do not know how to further
disassemble this.  Can someone point me in the right direction?

Thanks for all the help I'm getting on this list.  I really appreciate the
time folks are taking to answer my and other's questions.

Paul in Colorado