I've had three of these traps for about 20 years now and it seems I have to use it a few times about every other year, or so.  It has never failed me in clearing out the moles although it can take a little time to setup.  However, there have been about one or two times when the mole has dug under the original tunnel floor avoiding the trip area causing the failure of the trap to work.  Relocating the trap to another section of the tunnel has always resulted in trapping the mole.  A few tips on using based on my experiences:  Following the instructions on the box, I build a firm, narrow soil ridge, or mound in the tunnel for the trigger pan to rest on (this mound, or ridge, is what the mole pushes through to spring the trap).  If the soil is too dry, moisten it with a light spray of water until the soil can be packed tightly under the trip trigger pan.  With the trap catch latch set, handle the trap with the thumb over the top loops and the fingers under the trip pan directly under the trip lever.  By firmly pushing up on the trip pan directly under the trip rod, you are less likely to trip the trap when placing it in the tunnel while pushing the trip pan down onto the soil ridge.  At this point I usually use my other hand to push the trip pan firmly down on the soil ridge.  Make sure there is space under the area of the trip rod so that the trip pan can freely pivot (and spring the trap) when a mole pushes up on the other end of the trip pan at the soil ridge.  Place loose soil back in the tunnel around the trap so that the area is level and the trap is about half covered with soil.  Finally,  release the trip catch latch and put a bucket over the trap.  I always place a brick on top of the bucket too.  This will help keep animals from hitting the trap and sunlight from striking the trap area and scaring the mole off. Check the trap daily and if moles are active, you should have a hit in a day or less.  If not tripped after a day or two, set the catch, pull the trap out and check the tunnel and soil ridge setup and reset, or move to another location.  The trip pan can be bent down slightly to make the trap more sensitive but I really don't find this necessary.  I suspect that the moles that tunneled under my traps detected my scent in the soil or on the trap since I do not wear rubber gloves when making the ridges and setting/handling the traps.  I'm just lazy that way.  Overall - highly recommended.