I have similar worries and did consider the question you poised but TBH I think my safety and the safety of others would suggest replacement / cleaning. The sensors are around £60 I think. For the diagnostics I would pop over to yell.com and search for Garage Services in your area and get on the phone. Mines OSR. A "how to clean the ABS sensors" with pictures would be very much appreciated as would prefer to try this tack first..
Anyone done this ? A lot of my local garages have suggested the sensor "may" just be dirty..