Weed whacker or strimmer repair help.

Help please .
   
    I have a Stihl weed strimmer ,  whacker model FS 56C , and the gear head at the business end has had a few hits on unseen rocks and stumps. The upshot is that the square drive inside the head has lost two of its sides and now the square end of the flexi drive is not fully supported . My first view is its a poor design , a square peg into a round hole and the weak points are at the corners !!! anyhow thats my gripe.
    So , i tried to get the bevel gear shaft out of the head with a homemade puller but it just locked up , the large sealed bearing almost came out of the ali casting but not fully . All i need to do is buy another drive shaft , not a complete head unit .
    Has anyone repaired a gear head , if so what are the procedures please, special tools  or homemade tools .

Thanks

From what you describe, you want to take that to an Elite dealer, they might be able to get you repaired for free. If you do it yourself, any warranty you might have will be null and void.

Stihl products are about the best designed on the planet and they do stand behind their products better than most.

I have several Stihl products including an F90 Pro trimmer and I even have the blade for cutting sapling trees with.
I've got lots of mini boulders and I've never hit the head on one, I've dinged the tree blade on them but never the head.

Thats why i bought a Stihl , i think they are the best .
I take your popint about taking it in . Well i meant the blade has hit stumps and rocks and i,m trying not to but its not easy. It feeds back to the square drive shaft and after a while of hits its just fractured the square socket on the splined shaft in the ali head . Ive never had this before .

    Thanks for the reply and advice