Cooking With a 1,000 Watt Electric Grill?

I have a 1,000 watt electric grill (Farberware Open Hearth), long since discontinued. No customer support available. This grill has the heat source coming from the bottom and there is nothing on the top. How do I adapt recipes that might be written for a 1400 watt grill?

For instance, I grilled chicken breasts and it took twice as long to cook as the recipe indicated. Bearing in mind that Target's Gold N' Plump chicken brand runs large, how does one adapt a recipe? The recipe called for 20+ mins. Took me closer to an hour. I spent a lot of time wondering if they were ever going to be done. Well, they were delish and they were done, but that was a lot of time spent wondering unnecessarily about a meal.

Holly from Richardson, TX