This isn't too unusual. Since the chain has been running with slack for a while, there has been more wear on the chain and sprockets than there would be with a properly tensioned system.
There's a couple of ways to address this. One is to do nothing. Eventually the chain will hit the case in this area (the bolt boss cast into the case). Just let it wear in and let the filter catch the aluminum. The amount would be quite small. You could also clearance the case a bit. Remove the idler sprocket, shaft, bearing, washers, stuff the hole in the case with paper towel. Mask the area like a dentist doing a root canal. Use a very sharp chisel and CAREFULLY remove material. Some have used a dremel, but this creates enough dust it's hard to catch it all, and takes about 3 oil changes to flush all the aluminum. The "let it wear" method puts less aluminum into the oil.
You could also get a new/better condition used chain and sprockets from eBay or the dealer. Measure the chain according to the specification in the manual - the spec is found in the top end section of the older manual and I think the same place in the new manual, adjacent the cam chain spec. In my experience changing the sprockets will get it back to normal - but measure the current balancer chain to be sure. The chain is expensive new, the sprockets slightly less.
Hope this helps.....