The whole idea of build-in 1 ohm bias measure points is that you measure the dc-voltage!!!!
If you start measuring the current, you got wrong numbers because that's not the way bias measure points are build for. It is simple standard electronics but a bit too much for this thread.
If you're really interested in the the explaination; google: aiken amps, he has lots of info on tube tech related matters.
Or visit your local amp tech for a proper bias .

Here we go....

The additional 0.2 ohm resistance of your test leads would only come into play if these leads were in SERIES with the one ohm resistor. This is  not the case. When you take a VOLTAGE reading with the multimeter, the total resistance across the leads, INCLUDING THE BOX, is probably on the order of a thousand ohms. So the additional 0.2 ohms of the leads would make it one thousand point 2 ohms. This will  not change your readings.

What you do need to be aware of, is not all the tubes current comes through the cathode. Some leaks through the grid, and this is what you will NOT be measuring with the cathode bias method. The leak is usually small.
So when you measure 32mv you have 32ma coming through the cathode. The total tube plate current (including that going through the grid) would be like 35ma or so. Its OK to make this estimation, because actually measuring the plate current can be dangerous, but is easy to do if you are so inclined

I am in 100% agreement to use your ears, but I was getting a smoother sounding tone up past 42ma on one set of tubes. That's fine, but one arced on me when they were that high. So, you want the best sounding bias setting that is up to or below the recommended heat dissipation of the tube in question.

Exactly!

Fred,
I would suggest not using the current measurement at all. If you have a 1 ohm shunt resistor installed, as I believe there is in the OTS, the mV reading in directly proportional to the actual current. Most multimeters have an internal fuse that can blow  without the user knowing. The voltage reading is much more reliable. If you are reading 26mV that is probably what it is w/in the accuracy of the 1 ohm resistor (1.2 ohms is really unacceptable for this purpose, the resistor for bias measurement should have a 1% tolerance). If you are really in to using this bias method and the resistor is really 1.2 I would replace it.
Also try another meter that is known to be reliable.

Good Luck

thats what i thought. I have the red probe in one of the red sockets and the black probe in the centre black socket, which should measure just the one.

I also had 25-26mV when I checked my bias. I increased it to 30 then 35 mA. There was no noticeable change in amp tone for me. It is possible that the tubes will run a little cooler, but my tubes were not running abnormally hot at the original bias. I am sure Nik has his reasons for this bias setting.

And...Although the bias check feature on the OTS seems to work fine. I use an AMP-HEAD Dual bias tester on my other amps. It has dummy sockets that plug in the tube sockets and then you plug in your tubes. It is pretty convenient for a quick bias check. AMP-HEAD also makes a device that measures plate voltage that will piggy back with the Bias tester. You don't really need this stuff if you change tubes infrequently. But if you change vacuum tubes frequently they are nice.