I measured the DC response of the Green PD
Power into PD at DC (green laser pointer) = 285 uW
Voltage out of PD = 552mV/(100x SR560gain) = 5.52mV
Photocurrent = 5.52mV/(241 Ohms)*3 = 68.7uA
Responsivity = 68.7/285 = 0.24 A/W
Therefore, since the responsivity is in the correct range for a Silicon PD at 532nm, the DC output is giving us sensible response to an input signal.
But, there is a 2.12MHz, 328mV oscillation on the DC output irrespective of the incident power.