Do as Wyatt suggests, check for loose wires and hit the switches with compressed air to dislodge any possible dust on the contacts. If that fails call Oneway and ask to speak to Shane. I went through this last week and spent 1/2 hour on the phone troubleshooting with him. Wound up ordering all four switches on a well-used 25 y/o lathe (on, off, forward/reverse and E-stop) as we couldn't isolate the problem. You will want to open up the inverter box to read any error codes as you walk through the process.