It is extremely improbably that it is the electronics because the worst that could happen to the motor if the electronics were bad is that it would either run at full speed or wouldn't get power to run at all, but neither situation would make the motor smoke. If the motor had been run under extremely heavy use (basically being overloaded to the point where it would slow down a lot or stall), then individual armature windings would begin to fail by burning out and resulting in less power and more heating -- once the process starts, it begins to snowball. One indication of this type of failure is that the motor will not start running when the shaft is in certain positions because of open windings, but sometimes if the shaft is rotated slightly by hand while power is applied, it may begin to start rotating. Depending on the condition of the motor at this point, it may either to continue turning with reduced power or it might just turn a fraction of a turn and then stop again if several of the windings have burned open. If this turns out to be the problem, the motor (or at least the armature) would need to be replaced. Rewinding is usually not economically feasible on motors of that size.
Bill