Forced air heater problem

Hopefully someone here can give me some ideas on what might be wrong with my Day and Night heater (about 10 years old). Every few days it fails to come completely on and it flashes a Ignition Proving Failure warning message. But the other 98% of the time it works perfectly.
The details: - It seems to do this in the early morning when it is changing from the lower night setting to the higher day time setting. - Removing power to the heater, waiting 5 minutes and turning it back on seems to always fix the problem (based on three to 5 times) - The thermostat was replaced and did not fix the problem - The sequence is: low speed fan comes on, electric igniter glows, gas jets are ignited, a few seconds later the gas is shut off, error message flashes, fan continues to run for a while, then the sequence repeats.
Thanks for any ideas that I can try for myself.
-Jim
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snipped-for-privacy@yahoo.com wrote:

That must have a separate flame-sensing probe.
The probe may need cleaning/replacement. If the probe doesn't report correct electrical signal from the flame ("flame rectification"), the control will signal failure to Prove Ignition.
Jim
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snipped-for-privacy@yahoo.com wrote:

You might try also posting this question to alt.hvac.
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