[Mondial]

Yes, the positive of C38 should go to ground and the negative to one side of L17. The center tap of the power transformer should connect to the other side of L17 and the field coil of the speaker L18.

Note the speaker has TWO field coils, L18 and L19. L18 should develop a negative voltage across it. What resistance do you read from the center tap of the power transformer to ground? Should be the same as across field coil L18.