I will try to replace the cap... but the hum is back... tried 10 differente preamps and i getting 60 Hz humm...
Because the hum is not related to C11, but to some grounding issues with metal parts of the microphone.
Wrap it in aluminum foil (simple test) and the hum will be gone.
Is the filter cap for the polarization voltage connected correctly (GND) and of sufficient size?
Shure refused to send a service manual to me, so it's hard to tell where the low range is filtered.
Have a look at the input stage, it should be very high input resistance (>60MOhm) built around a FET. If not, as mentioned above, the original capsule might have an amplifier built into. Is a wire with supply voltage going to the capsule?
A coupling cap would needs to be very small (<100pF) to affect the low frequency response, as the capsule itself is around 60pF.