Gerry:
   I have one that is not as nice as the Ronco and it works just fine.
You may want to check each tray individually and rotate them if
necessary.  I have dried just about everything with it.  Fruits are much
better if you stop them before they are crispy.  As they cool they get
more dry and if you let them go too long they taste more like paper than
fruit.  Also, I found that apples are much better if you peel them
first.  The skins get awful if left on.  Just my own personal opinion
and experiences.
Beverle