The Dell Latitude 7400 and other similar models have a common problem where the touch pad will not press down properly. For example, if the user is pressing the touch pad to perform a left click, the touch pad button will stay clicked without the user pressing down on the touch pad. In other words, the touch pad will get stuck. To fix this issue, the touch pad or the entire palm rest will need to be replaced. Another fix is to sand down the sides of the palm rest, so that the touch pad will not stick the palm rest. The touch pad will have more room to return to its original position. Just a little bit of sanding of the palm rest can unstick the touch pad. In order to sand down the side of the palm rest, the touch pad will need to removed. The removal of this part is straight forward, however. Just a couple of screws hold down the part, and once these screws come out the touch pad should freely come out.
There are 7 screws holding down the touch pad. The internal components do not have to be removed in order to sand down the sides of the palm rest
Here is the touch pad removed from the palm rest. The sides of the palm rest of where the touch pad sits will be sanded.