Please help!

We have a brand new black glasstop cooktop and something is stuck on the surface. It is under one grate and around the burner. I tried using the cream solution provided by the manufacturer and I folowed the directions. But, it is not coming off or loosening up. The instructions said to use a damp cloth or paper towel and I used a paper towel. I am afraid to rub too hard with a paper towel for fear of scratching the black glasstop surface. So, what can I use to lossen up whatever is stuck on there?

 

Thanks, Mark