This can cure up to 75 per cent of the rattle usually. If it doesn't cure it completely, then the B or C clutch outer, which features cush drive springs rather than rubber is the answer, plus new rubbers on the primary chain hydraulic tensioner oil feed. Also, the tensioner can crack or become hard and as a result oil pressure is lost to the tensioner. Thus the primary chain is not properly tensioned and this aggravates clutch chatter. With worn rubbers pressure can go down from the direct 64-74 psi at 4000 rpm to about 30 psi.
Fourth gear is a problem, mostly fixed under warranty by now.
If your bike shifts well, leave it alone. If it shifts badly, the box will have to be inspected. The problem is with fourth gear which will need replacing. On early engines the track on this gear was not machined correctly and wears rapidly. Some bad shifting can be put down to the gear pedal pivot which wears rapidly on all machines.