When i start it and the kick arm returns to its position I get a whirring noise like something catching. If I pull the arm back slightly it goes away. I have had to reposition the arm to rest against the casing to stop the noise. What is going on in there..is a return spring worn? A stopper on the arm would be a quick fix.

Only real way to tell is take it off and have a look inside!! Otherwise your just guessing.

I bet the boss that locates the spring is broken,As Slice said pop it appart to know for sure.

Here was the problem..this needs to sit very tight on the kick shaft..the one I had seemed tight but after fitting a new one I saw the difference. Only ZAR20 to replace..kickstart back to normal.