There is an easy way and a hard way to ascertain if it's the:
2. Motor and assembly
3. Sticking in the window rails.
No need to remove the door panel at all just yet but you will need:
A long set of battery jump leads, long enough to run from the battery to the rear inner door area and two separate insulated wires that are taped to each positive and negative alligator clip of the jump leads at the door end.
Strip the two other ends of the pair of wires.
Do not connect the jump leads to the battery yet.
Remove the door pull handle/ switch cover from the door panel ( rubber cover and two Allen bolts). Lift it all out and disconnect the window switch from its terminal block.
You will see 6 contacts on the block, 4 in line and 2 parallel. The 2 contacts in the center of the 4 in line contact are the power to the motor up and down ( reverse polarity for opposite up / down operation of the motor and assembly)
Now you have it all ready make sure the jump leads are insulated from each other and also your bare wire ends are well separated.
Now connect up to the battery terminals.
Using the two bare wire ends, touch the two central contacts and see if the motor operates... if it stops, reverse the wires on the two contacts and watch the window move down. Reverse the contacts again and watch it go up.
If the motor just clicks either way, it is seized and needs replacing,
If it moves slightly or struggles, then it's the window rails and seals that need lubrication. If it goes up and down freely when making connection with the wires to the contacts, then the switch is duff.....
Simple but effective
Like I said, an easy way and a hard way
It only takes ten minutes to check total...
Or you can chew on removing glass, motor, door panel, assembly and switch for two hours and get the same results, then having to put it all back together before it rains