Thanks for your help all. Glad to be back in action.
The reason I set it to DC is because (so far as my newbie self can tell) it says to do so on page 38 of the Crack manual I have. One of the voltage check steps says "Turn the chassis over and reconnect the negative lead of the volt-ohm meter to the ground bus. Switch the meter to read DC volts on the 400V or higher scale." Then it goes on to give a list of terminals with the header "Voltage (VDC unless otherwise specified)." It says terminal 1 should be 90 VDC, 2 should be 170 VDC, and so on. That's why when I saw 2.5 VDC on terminal 1 I got worried.
But I'm obviously missing something major (and probably very elementary)!