Gentlemen,
PLEASE, let me interrupt. The Lincoln has NO spark ignitor. This oven(Lincoln II) much like the Lincoln 1600 is a HOT Surface ignition system.
The sequence is to heat up the hot surface ignitor and then flood it with gas. The return leg on the ignitor is linked with a flame detector that sends a millivolt signal back to the ignition controller that allows the gas valves to remain open.
Your “clicking” noise could come from a multiple of items:
*Burner combustion blower motor, this is the motor that looks like a hair dryer. Your centrifugal switch mounted in the top of this motor could cause this noise as it moving into position to close the circuit to allow the heat sequence to begin.
*One of your solenoid valves could be also be going bad. Most valves are rated at 140,000 cycles; per BASO. Figure a solenoid valve cycles 1 time a minute, an oven is operational 12 hours a day, thats 262,800 a year. Basically according to BASO, the valve should be replaced every 6 months.
*Depending on the year of your machine the internal cooling might have a obstruction on it, when the air flow in low; as with start up the FOD(Foreign object or debris) is resting against the fan. With increased airflow the FOD is suspended away enough to cease the noise.
Good luck.