Stihl BR 550 running poorly

[precision8m]

I have a Stihl BR550 blower that has many years of use on it. It starts up fine and runs ok for a few minutes, but then it bogs down and wont run any higher than idle with throttle fully engaged. If i keep the blower on and push the primer button, the blower comes back to life a bit but then goes back to bogging down. Sounds like its not getting enough fuel? Has anyone else had this problem?

[rlitman]

Since you said you've had it a few years, I need to ask:
have you done the valve adjustment?

[precision8m]

I have not. I took it to a mechanic last year (I dont use it much) and he said he looked through everything and it looked fine (he was probably lying to me). I do not use ethanol fuel in it. What is the valve adjustment?

[rlitman]

This isn't for this blower, but you'll get the general idea from it:
http://www.youtube.com/watch?v=waPf0oDAVOg

IIRC, these engines need valve adjustment every 100 hours or so.

[precision8m]

It ended up being that stupid screen on the exhaust....