Thank you for your inquiry regarding this item from Prime-Line Products. If this is for a new install, the step-by-step instructions included with the kit will instruct when to install the roller assemblies into the track, and then, when and how to fasten the brackets attached to the top of the pocket door to the rollers inside the track. If your inquiry is in regards to replacing the roller assemblies on an existing track already installed in the opening, it may be that the track was installed incorrectly from the very beginning. If that is the case, the track end will need to be cut to make it about 1-1/2” shorter than the finished opening. The roller assemblies will then be able to be tilted into this 1-1/2” opening between the end of the track and the door side trim (stile) by inserting the first set of wheels and then the 2nd set of wheels. They should then be rolled to their approximate place on the track where they will mate with the door and the mounting brackets on the top of that door.
That being said, the solution is to cut the track back with a Sawzall or hack saw. By inverting a metal hack saw blade in the Sawzall, (the more teeth the nicer the cut) they can cut upwards until they cut through the track, thus exposing the needed space to install the replacement rollers.
For additional questions regarding this item, or any other product manufactured by Prime-Line Products, please call their toll free number at (877) 649-9740, or contact them by email at firstname.lastname@example.org