Dosydave

Thanks for the responses The muffler on my machine has a fixed non removable exhaust pipe, there is no hex nut. The stihl parts diagram for this model shows 5 variations of muffler all with spark arrestor but none of them are the same as mine. I'm thinking that the muffler on my machine may not have a removable spark arrestor. It gets bogged at high revs and a clogged spark arrestor could have been the cause. I've tried all the obvious things so I will have to go a bit deeper.

Where is the spark arrestor screen on a Stihl FS38 trimmer and how do I access it? I've removed the muffler but its a sealed unit with no access points other than the the inlet and the exhaust pipe. There must be a spark arrestor screen somewhere but I'm jiggered if I can find it.