My shindaiwa 488 ran and cut great one day . The next day started great as usual but idled as the brake was on but was not . It will not rev and again acts as brake is on . Chain spins free with my hand but never turns when trying to rev . I know how this saw runs and sounds and it is like brake is on . It will sit and idle til it runs out of fuel and will not ever die while trying to rev it but will not rev . I have changed plug and checked fuel filter . Going to look closer at clutch this morn . Don't know where else to look other than carb but do not want to go there yet . Want to rule everything else out first . Help wanted .