[Arran]

 It would be DC for certain, field coils always are regardless of whether they are used as a power supply filter choke or no. But you don't really need a volt meter to test it, you can check with an ohm meter to see if there is continuity between either end of the field coil and the speaker basket, it will read with a very low or no resistance on one end, and the resistance of the field coil on the other, just make sure the set is left off for a few hours first to discharge the filter caps. It's possible that it may have left the factory like that, but repair or replace the wires, if possible, and put that cover back on, it's there to stop unknowing persons from touching the wires.
Regards
Arran