Trackpad Sparking

Have had my MBP in at the Apple repair shop so as to have the hard drive checked out and teh sparking noise fixed. It came back with the hard drive checked and in full working order. The electronic sparking noise persists, apparently it is from the trackpad. I will be taking it back in. Has anyone else had similar problems and found a solution please? MBP is late 2011. Bought refurbished from Apple.