The problem is the worn pad. You will have to replace the pad. If a new one is available from the manufacturer. The glue on hook-n-loop conversions don't work very well, as you found out.
Black and Decker tools are more use it then throw it away. Better tools have replacement parts available. I have a 5 year old Dewalt and replaced the pad at least twice. The sander works great. But, I have a tendency to be hard on the edges of the pad.