Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
If the glass is shuddering when moving down ward then there is some thing binding the works .
Or the motor is failing .
You will have to remove the inside door cover and inspect .
Most common is the window armature which is cable operated and the cable pulleys break and cause you this type of problem.
In most cases it better to replace the complete window armature..
Attached is a pic and marked red the parts tend to fail ..
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Kind regards Greg.