Hey Tom,
sorry to disappoint you, but it would have been very surprising if it had a brushless motor or an induction motor. You already can tell this by the fact that it has a speed regulator. If it was an induction motor, to have speed regulation, it would need a VFD internally which would make the device extremely expensive because it would need, at least internally, three-phase electricity, and if it was a capacitor start induction motor, such motors cannot have speed regulation. So of course, and is to expect, this is a universal motor with carbon brushes: