It is an up and over roller door and has a turn handle lock. Its key is just like a front door with an number of cutouts that operate the tumblers( if that is what they are called) It was fitted before I bought the house and I have lived here for 14 years. Over the years it has worked OK but now and then it refuses to turn open. I used WD40 and normally that worked. But today it has not. I have a second key and that does not work also. So I think the barrel has worn to the point that the key cutouts dont fit the key profile anymore as they should. So the only solution I can think of is drilling the barrel but will that be enough to be able to get the lock mechanism to work? Will normal drills bits do the job?