pull cord jamming on honda izy ?

We have a Honda Izy lawn mower. The pull cord is jamming - I'm not sure if this is something to do with the pull cord spring, or a problem with the brake release. I've tried to unscrew the cover to have a look at the cord but having a little trouble unscrewing the bolts... but presumably I should be able to take the top off and check the cord.
I can see a small plastic white piece stopping the mechanism inside.
I took the mower to be fixed last year for the same problem but keen to try and do it myself to save money!
Thanks for any help or advice.

Hendo
April 2015