There are meters that will test for voltage, but probably if the guy could draw a 3/4" long spark, he said it was OK.... and it was.

Cad cell eyes can be tested with an ohms meter. In the presence of light, the ohms drops to about 300-1300 ohms.

Cad cells are checked through a process of elimination.

I guess what you are saying is that a transformer is a go or no go. It either has 12 or 14,000 volts or it has non.

No, they can get weak. I've had alot of warranty returns of "weak ignitors". They were supposed to NOT get weak (either work or not), but Beckett has conceded that they can get weak. Transformers usually last for hundreds of years or they burn up.

Very Simply.
I saw the repair guy test mine.

OPEN up the igniter box and rotate it over so the springs are
pointing up, not down touching the two rods.

TURN ON the heat so the pump is running, The repair guy
disconnected the wires to the pump so he could leave
ot on for a few minutes. Otherwise only do the test
for 30 seconds so you don't fill the chambre with oil
spray.

Hold a screwdriver across the two springs holding
the insulated handle. Slowly pull the screwdriver
away from one spring and observe how far you are
able to maintain the arc.

A good coil will maintain the arc way over an inch.

Less than that and it is weak.

Note that igniters may get temp sensitive over time.
And for $35 it may be best to change it.

The photo cel will turn off the system in 40 seconds
if not exposed to brite flame ;ight.

Note that it won't even start unless the eye sees no light.

My beckett 1a will start fine, the cad
lite kicks in on the 40 seconds if the
flame is not seen. The control module
takes care of this.

Yes, the primary control will shut off the burner motor after 45 seconds on the old type and 15 seconds on the new type.