DC Machine Ouput Voltage Waveform
It is a DC motor


I think it's more likely a DC generator so...

When you had your generator brushes half way between the north and south magnet poles the flux is such that there would be no brush arcing and you would get a smooth voltage waveform as per diagram (B): -



Now, with the brushes moved to the new position, there will be flux problems and arcing hence there is a discontinuity as the brush shorts out coils that have voltage across them. This will mean that diagram (A) or (C) is the resulting voltage waveform.

As this sounds like homework I think you should decide on which of the two is correct - you need to figure out whether the voltage at the new A position is now greater based on current flow shown on the windings.