Finally I got clear answer for this question.
It happened that I run ABS printing ( extruder temperature 235 Bed 100)
a few hours without cooling fan for extruder.
Suddenly I found something happened as like in the pictures attached.
Blue bracket holding step motor got very hot and gave way to the weight of step motor.
It got cracked as I pushed from the other side to fix it.
I hope someone will give me idea of how to fix this bent bracket.
Geeetech do not sell this part. Do I have to print this part by myself?