Thank you for using ManageMyLife.com. I am sorry to hear of the issue you are having with turning the dishwasher on, I know how frustrating that can be.
Since this unit is mechanically controlled vs. electronically controlled via an electronic control board, it makes troubleshooting easier. The most likely culprit for the unit not coming on would be the timer, behind that would be the latch, the rocker switch, and lastly the motor. I'm curious to know if you hear any sounds when you go to set the timer, like the motor humming or the like.
Without testing these components with a multimeter for continuity, we won't know for sure which one is defective. I would recommend testing these parts for continuity to determine which part is at fault before replacing parts.
If you would feel more confident have a Sears Home Service technician help assist with the diagnosis/repair,
to be directed to the page to set up service.
If you have any further questions or inquiries, please don't hesitate to ask. Thank you for using ManageMyLife.com.