THERMAL DYNAMICS 50 XL PLUS plasma cutter not working

Was Working Fine ,Then Just Quit Cutting.
I Checked The Off & On Switch & When I Turn The Power On A Green & Yellow Light Comes On.  When THe yellow Light Goes Out * & I Pull The Trigger It Shoots Out Spark.Then I Try To Cut & Immediately It Quits Cutting.I Go Back To The Machine & Yellow Lights Back On. Machine Wont Work When Yellow Light Is On.