Do the motors still run when the AMS tries to reel filament, if that’s the case you have to just replace spring mechanism that grips the roll, because it may have broke.
If motor doesn’t work then you have to replace the motor, there is no way around it if this is the case.
Here is a model that may help if the spring mechanism that holds the filament roll is broken, hope it helps.
Glad if this helps with your problem. 
