83 240D Starter motor spins, but doesnt turn flywheel

[Carrameow]

Once in a while , i turn the ignition key,I hear the starter motor spin, but i dont believe the solenoid has driven the gear to mate properly to the Flywheel.
I hear the motor spin, but feel nothing coming from the gear to the Flywheel.
Does this mean the starter motor solenoid is going bad-not doing the plunging thing- or that the solenoid is plunging, but the gear is just missing the correct poistion on the clutch?