Odometer no longer working

I have a 1994 Saturn SC1. Bought it for next-to-nothing and three years later, it is still running.

I noticed last week that the odometer had stopped working. Since the mileage on the display is exactly 3,000 less than the mileage on the oil change sticker (suggested mileage for next oil change), it would seem that the mechanic might have bumped some cable while changing the oil the last time. Well, I went for a new oil change this afternoon, and mentioned this to the head mechanic. He seemed to think that the evidence was circumstantial, and that the odometer had not been broken during the last oil change. He suggests a sensor might be blocked, or something mechanical in the dashboard unit itself.

What is the probability that the mechanic might have broken the odometer? Are the odometer cables anywhere near the oil stuff? Could the odometer cable been broken by the hydraulic lift? Or is it likely that it just broke on its own?

Thanks for input, guys!

If the speedometer functions but the odometer doesn’t, it means there’s a problem with the speedometer head and requires replacement.

Tester