The speed of X7 is not accurate, there is no resistance, no speed, low power and other speed, resistance, power related faults can be mostly replaced by light sensing stickers, gaskets, speed small board and motherboard to solve.
Replacing the stickers, gaskets video: https://youtu.be/cMWYyqfJ0b0
Replacing speed small board video: https://youtu.be/6yktrn9Yduk
Replacing the motherboard video: https://youtu.be/524-r1BwTKs