I have a Potterton Neataheat 10-16 circa 1986 Pilot has difficulty lighting?

The gas on my property has been disconected for 3years. On reconnection the service man had trouble getting the boiler to run. He turned up the gas pressure at the inlet to the boiler and it eventually fired. There is good vacuum. Good spark. When it does light, could take a few min of sparking it runs fine and even re-ignites without much trouble. I remember it uses to take 3sparks to ignite. Is there anything Obvious like a blocked pilot hose