Husqvarna 550xp mark2 weird high reving issue?

[biggimmer]

Hi, just wondering if anyone has an idea what might be wrong with my saw.

550XP mark 2   The first time the saw played up was after a full day of use and it seemed to be revving irregularly and too high. So instead of hitting top revs and being happy it sounded like the rev rate was 'irregular' and it wasn't sounding happy at all. So I started it the next day to see and it ran perfectly...revving correctly and sounding perfect. I used it for a couple of days and it didn't miss a beat........then it did it again after starting and running fine for about 5 mins.

Any ideas?

[5thelement]

Crank seal. 

[Stubby]

As above .