Anyone know much about these?

Are they both supposed to have an adjustment screw in or just the front one?

My cable conectors are black at the front one, white at the rearwards MAF, that right?

How do you reset these? Can you wind the adjuster all the way in and then back out.

I had a slightly sticky flap, so I opened them up and put a little WD40 on the spindle bearing, and it now moves freely.

I have an exhaust gas analyser if that helps.

Recent full services, static timing set to 12 deg BTDC.

Can I test them with a multimeter?