Product review (2 stars): I had the same problem as another reviewer when taking ...
I had the same problem as another reviewer when taking off the dust cap the sensor cover comes of too. Talked to Extech they said it was a problem . I am sending it back which is a pain and I  needed to use it this week. I cant tell how well it works I didn't get that far. I think they should just send a new unit and  then I send back the broken unit. Not sure if I will get another one to replace this one