If the coil is disconnected from the fuel pump, the oil won't be allowed through so you can see the ignition spark.....best to keep the burner pointing into the boiler, even use a mirror!
We don't know the state of the flue passages through the boiler so far...just from the descriptions it seems that the burner was lighting up, then going out, then trying again?
That could indicate too much air blowing the flame out, an interrupted fuel supply or flue obstruction possibly.
A photocell fault would usually allow the thing to light, and then shut down after a few seconds.
John
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local