How to bias a tube amp with a Multimeter

I thought that turning the screw would create a contact that would activate the probe point.  Your amp otherwise does not appear to have a switch to activate bias testing.  I could not think of any other reason why the test point has a groove that makes it appear to be a flat head screws.  

The picture you have of your VOM has, for the selector knob, 40A and 400A, which I assume is not 40 or 400 amps (crazy high current), but is 40 and 400 milliamps.  Select 400A and try testing, if the needle barely moves, then select 40A.  

^^^ Thinking about what he's saying..Try backing one of the + screws out & see if it comes all the way out or has a stop point..If it has a stop point move the ground screw out as well & retest,you never know...

@larryi @freediver thanks for your suggestions. I will try adjusting the MM, and the screws on the amplifier tomorrow to see if I can get a reading. Thanks for your assistance!

Here ya go!

https://www.galvinpower.org/bias-tube-amp-with-multimeter/

Measure the resistance at test points + and - with the amplifier powered off. If you cannot get any resistance readings, you cannot bias the output tubes.

If this is the case, the problem may be a bad meter probe or the amplifier test point is not connected to the cathode resistor.