Will start fine most of the time but once every few days it will not start. When the key is turned all dash lights etc work but no sound, not even a click. It will eventually start but cannot be depended on. Took it to the Chevy dealer who told me they could not diagnose the problem because it was starting properly that day.

Well, hello, Sally!
And welcome aboard!
The dealer should have check for faulty connections at the battery and at the starter.
Do you know if they inspected the cable ends at the battery?
If the battery and cables are good, you'll likely need a starter: the solenoid is failing.