>>Do these voltages look good

It's quite low, but as yet, it's difficult to tell if that's because the battery has gone West, or if there's a bad connection somewhere.

One way to tell is to repeat the test, but, put the positive wire onto the positive battery post (the post itself, not the terminal), and put the negative onto the glow plug 6mm nut. When the circuit is energised, you'll then measure the voltage dropped between the battery and the glow plug. If more than, say, 0.5 volts are being dropped, then, there's a bad connection somewhere.

If the voltage drop is OK, check the voltage across the battery posts while the glow plugs are energised - I would hope that the voltage would not drop to anywhere near 10 volts, which is a reasonable cranking voltage, not glow plugs as the only load.