Here we are:

You don't need fancy equipment to adjust this amp. Measure the DC voltage at the power fuse, should be close to 56V, and adjust the trim pots VR1 and VR2 for exactly half this voltage (~ 28V) at the + side of the output cap. You have enough precision with your actual meter for this.

Now I will suggest something you will not find in the service manual, just for those like you, with a less sensitive voltmeter.

For bias measurement, you will remove the power fuses on the amplifier board (W15-060), and connect your meter in DC CURRENT mode, the + probe on the supply side of the fuse, the - probe on the amplifier side of the fuse. Adjust the trim pots VR3, and VR4 (with the meter in the corresponding fuse for the channel to adjust) for 40~50 mA reading on your meter. This corresponds to 1 mA in the input stage, + 5 mA in R13, + 4 mA in the driver stage, + 30~40mA (15~20mV / 0.5 Ohm) in the output stage. Adjust the Bias with no input signal.

Set your meter in the highest mA range when you will power ON the amp, since the initial current in the output capacitor may exceed the 250mA range. If 250 mA is your highest current range, connect your meter at the fuse but temporarily shunt your meter with a jumper, for a few seconds.