Stihl FS45 string trimmer bump knob - cannot remove

now, if you were to lock the black plastic bumphead in vise, and turn the nut to the left it should unscrew right off. If the shaft is turning in the tube,
then the bump head is stripped out. Because the two mating sides of that look like this:

DSCN6221.jpg

DSCN6222.jpg
 
You could remove the tube from the engine and try to clamp on the drive cable, but you would just destroy that too.

You could just get a good looking female relative to bring it by a Stihl dealer, and they would just zip that little nut right off with an impact wrench, if it isn't too boogered up, and sell you a new head, and you could be trimming tonight, and they probably wouldn't charge you any labor.
 
Place a small flat-head screwdriver through the holes in the plastic deflector and the thrust plate below it. This locks the shaft in position to remove the spool head.

Turn the nut counterclockwise.
 
Yes, exactly! This is what I have been trying to tell you. If the other end of the drive cable was attached to the motor end it would make the piston move. This is not happening!! This nut will just spin in either direction, left or right just by holding the cutting head!! Actually, you don't even need to hold the cutting head!!!
 
dukerocks said:
Yes, exactly! This is what I have been trying to tell you. If the other end of the drive cable was attached to the motor end it would make the piston move. This is not happening!! This nut will just spin in either direction, left or right just by holding the cutting head!! Actually, you don't even need to hold the cutting head!!!
Click to expand...

Turning the cable will not turn the engine. Why you ask?

Because the cable goes to a clutch.
Same type clutch that you would find on a go cart.
 
No, there is a centrifugal clutch on the other end, the drive cable only locks to the engine when the engine rpms reach a certain level.

But either way, if you can hold the black plastic trimmer head in your hand, and turn the nut to the left, then you have a problem in the trimmer head.

Cheaper weedeaters did not have a clutch, and their cable was directly attached to the engine.
 
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