Y-axis moves fine but cannot home

[exxosuk]

When I manually move the bed with the Y+- buttons it moves fine. But when I home Y-it sounds like the motors are stalling as it cannot move ?

I have tried adjusting the bump sensitivity but the bed even moves a tiny bit tour just sits there growling like the motors do not have enough power to move the bed.

So is there a separate amperage set to the motors when homing as opposed to when manually moving the axis ?

I also just tried lowering the current to 200mA and the motor just growls again as opposed to moving. So again it seems like the homing current is different and the operating current ?