Laser Printer Problem. When I make BW and colored copies on my Samsung color laser printer CLP-500

Question

When I make BW and colored copies on my Samsung color laser printer CLP-500 it leaves a gray ghost on prints. Should the unit that catches old toner be replaced or emptied periodically? Any thoughts?I went through cleaning toner areas and rollers with Samsung tech on the telephone. Plenty of life left in the transfer belt.