Greetings Santosh,
See these links on my website for some info. Right click to download to your computer.
https://home.comcast.net/~richmz/onlines...ration.pdf
https://home.comcast.net/~richmz/onlines...%20mod.pdf
https://home.comcast.net/~richmz/onlines...cedure.pdf
The rattle is likely due to the rear channel fabric worn or missing. It is a common problem on these as the fabric rots away over time.
In order to remove the glass/frame assembly you must remove the door inner panels. Remove the end cap first. You then need to remove the upper inner stainless steel molding, several screws, then lift away from the door post. You do not/cannot remove the outer SS molding until the glass is removed. Not needed unless being replaced of restored. If needed, it will be held in with very small screws in 3 places. The front screw will be covered by the glass frame. The glass must be out to access the front screw. Remember these steps for reassembly later if you remove the outer molding after the glass is out.
At the sash(the lower frame that holds the glass) you'll see the very small Phillips screws at the ends of the lower horizontal channel. If they are rusted you may have to drill the heads off, and later when the glass/sash assembly is removed you can repair, but be careful of the threads.
Position(crank) the window up or down to access the screws. There may be cardboard covers over the inner door skin at the front access screw holes. Simply remove them.
The rear screws are accessed after removing the large access cover door, held on with big Phillips screws. Some may be missing.
Then to make the job easier, at the end of the door will be 2 big Phillips screws which hold the Rear Channel. Remove both screws and drop the channel down and remove it from the door. You can raise the window up by hand to assist this step, then when the channel is out, lower the window down carefully by hand.
As mentioned, if the rubber gutters are dry and hard, it is difficult to raise the assembly up and out. You may have to break them away to get it out. They are really not necessary so don't worry. If you want to replace them see the procedure in the pdf procedure shown.
After the lower channel 4 screws are removed you can then lift the glass up and out. There will be one roller at the forward area which is in a curved channel as shown in the reference pictures that V10BOY linked to. This is the tricky step. You have to raise the glass up and tilt it at just the right angle. You'll figure it out by trial and error. Reinstallation is very tricky and may take several tries to get that roller back in the front channel, so patience is important at that step.
The ST-12 Service manual has some good info too.
Good luck,
Rich