How does the screw twist?
It depends on what your screw is the type of friends, if more than 8mm, we generally use, in the above welding a rod.
A kind of screw loosening agent, you can try. If it is slippery wire, and sub-specific circumstances, and sometimes can be destroyed by the screw head.
For the hexagonal head of the screw can be directly vibration (pay attention to strength), and then twist; if not edge of the case, you can use the saw or flat shovel of the head of the screw slotted with a screwdriver.
For the "word" and "cross" head screws can be upright screwdriver, vibration screwdriver back (pay attention to intensity), and then twist.
The screw does not come out is generally caused by rust. Welding handle or heating is a commonly used method of disassembly, but the small size of the screw is not applicable; preferably with kerosene infiltration for several hours, and then use the vibration method of twisting
