Harman Kardon TA-230 tuning knobs

Does anyone know where I can pick up original tuning knobs for my vintage Harman Kardon TA-230 receiver?
Can you send a picture of the other knobs to match?  Does it  have a round shaft (serrated with a small slit in the middle) or a "D" shaped shaft (smooth with a D shaped cutout).  I think I may have one knob if it is the "D" shaped shaft. It is brown with a brass concave insert.