the yellow measure is hidden under the air intake squarish hose. Twist and turn the hose from at bottom by rotating it anti-clockwise while twisting it free. then, pull lift the other end of hose free from it's two small plugs under the hose where it sits near the radiator. You can move it easily by lifting and taking. You will see the yellow tab under the hose.

don't loosen any bolts on the top of the transmission housing. You top-up trans. oil by the tube that the measuring stick goes in; you use a thin funnel to gradually pour oil in.

I think the difference between cold and hot on gauge is very slight representing maybe just 1/2 cup of oil. I have always had to re-check again and again and barely get the damned amount right. Leaks when 50cc too much, hardly registers on stick when 100cc too low.