removing old rollers from 30+ year old sliding glass door

Hello,

I believe that you will need to remove the bottom rail from the patio door to access your rollers. Your best bet would be to use a set of saw horses or a table to lay the door on while you work on it. There are screws that hold the frame together on the bottom sides of the door that you'll need to remove using a block of wood and a mallet to gently tap off the bottom rail of the door. Take your time since you don't want to damage the glass or the door frame. You might also want to consider enlisting a professional's help. See the related videos on this page for more information. Thank you. 

I believe the square tip screw not only holds the frame together but also the sliding door roller assembly. You'll need to carefully lay your patio door on a table or saw horses to remove the two bottom square tip screws. With a block of wood and hammer, carefully knock off the door frame from the glass. Then you can see how the rollers are held in place.