Have you got the manual? Before pushing the pin point button, make sure you have the coil at least a foot away from your target.Push the button and swing slowly over the target take note of the point where the signal is the strongest.Then swing over it again at right angle to your first swing and once again take note of the strongest signal.The point where the two signals cross would be where your target is. You can also use the depth guage as an indication as to the location of your target. When your depth guage is showing its shallowest it is directly under the centre of the coil.
Another thing which affects the pinpointing of the explorer is sensitivity. The explorer is very powerful and in experienced people run the machine on high settings thinking they are going to find more good targets. This is not so. Remember the machine has Auto sensitivity mode which when used will reduce sensitivity to suit the ground conditions.In harsh ground conditions you might have the machine set to say 30 but the macine has reduced itself down to a much lower reading as low as low 12. But when you pinpoint in high sensitivity settings it will exaggerate the size of the target, giving an indication that the target is under the centre of the coil but in actual fact it is not. This is more noticeable on shallow targets. You could also lift the height of your coil this will help narrow down you targets location.
For better pin pointing you could change your coil the Coiltek Platypus coil is a much better coil, giving better signal response depth and pin pointing. seeya Neilo