Repulsion-induction is short for repulsion start induction run. This
design
takes advantage of the fact that a series wound DC motor will also start
and run on AC.
At startup, brushes conduct electricity to the armature. When the motor
speed gets fast enough, a centrifugal switch withdraws the brushes. From
that point onward,
the motor acts in induction mode. It is possible that the brushes do not
retract; thus the motor does not enter the induction mode. You should
take the motor to a repair shop for investigation.

My experiences with repulsion-induction motor is with a 3 horsepower air
compressor in an autobody shop. The motor that we had did NOT supply
electricity to the brushes, they were connected together to "short circuit"
the armature. They could be adjusted by rotating the brush holder clockwise
or counterclockwise to set the amount of starting power needed. If I
remember correctly there were 4 brushes spaced equally around the
commutator, but I am not sure if they were all connected together or in
pairs. When the motor reached its correct RPM the brushes lifted off the
commutator and the motor ran without the brushes. This is why the brushes
would last a long time because they were only in use for a second or two
when the motor started up.