Petrol Lawnmower (Wraxall BS48)

Electrolux petrol lawnmower. It works to a fashion but is troublesome! Hard to start, hard to keep going but sometimes it does keep going and does a good cut. Ideal for someone who knows what they are doing with small petrol engines. Took it for a service and because of its age they didn't want to know and just wanted to sell me a new one. I suspect there is a fuel supply/spark plug problem which could be solved with know how. Fancy giving it a go??