Stihl FS45 string trimmer bump knob - cannot remove

Fish

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You mean the spring that is supposed to be inside?

DSCN6224.jpg

Show a pic of the back side and inside of your black cutting head.
 

dukerocks

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An impact would zip it off easily, which is why I suggest you do this. An air wrench, and an impact wrench, they are 2 totally different tools, drop by a Stihl dealer this morning, they probably wouldn't even charge you to try it.........

Got it all put back together, started it up, works fine, just need to get a new bump knob. Thanks for everyones input. Bob
 

Fish

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Works fine without the bump knob?
 

Fish

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Once you have it down to the nut, take it by a shop and let them tap it with an impact wrench.

Wow, this was post #10.....
 

dukerocks

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Works fine without the bump knob?

Well NO, not quite, needs the NEW bump head to work perfect. I fueled it up, started the engine, everything is good. Again, thanks for all the help to everyone. Bob
 

gaalford

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  • / Stihl FS45 string trimmer bump knob - cannot remove
I know this string is old but Im posting for anyone else that has this problem. My fs 45 is doing the exact same thing. Take a screw driver and pry the bump button off. take a grinder with a metal cutting blade or a hacksaw and cut a slot into the shaft. This will allow you to hold the shaft in place while turning the nut with a 3/4" inch wrench. For some reason the button seems to be clamping itself on the shaft of the housing and preventing it from turning. It's as if the bump button needs a spacer to prevent it from bottoming out. Even if you put it on loosely the button will tighten itself onto the shaft. I think it is going below the threads and that's why it doesn't twist back off. I bought a head from a tractor supplier that carried stihl products and it was supposed to be an exact fit. I'm going to cut a spacer from a plumbing tail piece tomorrow. Hopefully, this will work.
 

Jamesck

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  • / Stihl FS45 string trimmer bump knob - cannot remove
I know this string is old but Im posting for anyone else that has this problem. My fs 45 is doing the exact same thing. Take a screw driver and pry the bump button off. take a grinder with a metal cutting blade or a hacksaw and cut a slot into the shaft. This will allow you to hold the shaft in place while turning the nut with a 3/4" inch wrench. For some reason the button seems to be clamping itself on the shaft of the housing and preventing it from turning. It's as if the bump button needs a spacer to prevent it from bottoming out. Even if you put it on loosely the button will tighten itself onto the shaft. I think it is going below the threads and that's why it doesn't twist back off. I bought a head from a tractor supplier that carried stihl products and it was supposed to be an exact fit. I'm going to cut a spacer from a plumbing tail piece tomorrow. Hopefully, this will work.

Thanks! I read for an hour before I saw your post and now I am finished!
 

boydmiles

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  • / Stihl FS45 string trimmer bump knob - cannot remove
I know this is an old thread but it did tell me how to get the trimmer head off. I used the pry off the button method. Now why are they rounding out? Any way to prevent it from happening again?
 

dukerocks

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  • / Stihl FS45 string trimmer bump knob - cannot remove
Hi, do not have this machine any longer.

Thanks
 
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