Theford Tecma intermittently not flushing.

[dbutton]

Intermittently the Thetford Tecma will not flush. The push button green lights are lit & if you wait awhile, sometimes over night, it will work. This unit has a control box that I suppose could be acting up but it is $300.00 so I don't want to guess. Has anyone had this issue & fixed it? Do RV's really need an electronic flush toilet??