Maybe i'm wrong here but you probably lose the OSCCAL define on previous programming this device. Is any other never used before 12F675 close to you. If there's, read oscillator calibration within MPLAB an write it down on the chip (liquid paper on the bottom side). and now try with this one.

But maybe i'm wrong to say that there's no factory OSCCAL with those 12F serie like 12c508,509 or 12c671.

let me know