Amir, unfortunately VINAY is partly right... In part of the 250-700 Trex kits the ALIGN screws are well known for there shity qulity, probably in this case with the 250 it's a combination of shity screws and crapy tool

(dont you love my vocubulary?) any way both of you are right - It is recommended to get yourself a better tool rather than this toy allen screwdriver, plus there are some aftermarket upgrade screw kit for almost all the ALIGN models, if you wish to invest a bit of a money and live a better non bitter life with your heli...
Love You'll (that's a YOU ALL in southern accent

)