Switches are commonly replaced parts in power tools. A switch handles all on/off and variable speed functions. They also have a role in electric breaking; they can momentarily reverse electrical polarity, because switches use mechanical internals, they tend to degrade and wear out over time eventually requiring replacement. Some common signs of a broken or failing switch are: 1. Tool has completely stopped functioning - it not turn on 2. Tool operates intermittently, requiring multiple tries on to turn on, until eventually it 't turn on at all Variable speed function and electric aren't working properly Trigger Switch Part Number 153609-00 This switch is a compatible with the following compatible with DW708 Cut Miter Saw Types 1, 3 & 4 ONLY. Product Name:Trigger Switch Part Number:153609-00 Applicable Model:compatible with DW708 Cut Miter Saw Types 1, 3 & 4 ONLY. Note: Installation guide not included, we strongly recommend you professional installation. Please check as much as possible to make sure the item is what you need. Tips:The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use. Colour:As Shown Material:Plastic Package Contents: 1 * Trigger Switch Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. Note: The product may have a slight tolerance of 1-3 mm/1-729 g in size/weight, and the image color may differ from the actual item due to lighting.