Generally if you can roll it down using the button it is the regulator, not the motor. If the motor fails, it will just not move at all. A lot of the time, if you try and put the window up you can hear the motor running, inclining that the regulator is bad.
If it is only a single click you are hearing when holding the bottom down, that is just the window module setting. That click has always been there whether or not you have noticed it :P
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