Hi Karen I am sorry I cannot say whether you can buy a new sensor as mine as worked fine since I bought it,the only thing I can say is take the batteries out for 5 mins put them back and it should reset the sensor.
By Mr. B. Pritchard on 06 April 2015
yes we've had this "problem" before. select channel 1 on the sensor then reset using an unwound paper clip (not pen) as too thick then reset the base station in the same way. In this order should then be ok
By Coolandnew on 15 January 2014