I'm no expert, but it could be a few things. One is the door alignment and
tension of the springs. If one side of the springs is pulling more than the
other, it's provides tension on the closer and will not open. Even though
it's easy to pull by hand, the closer is more sensitive and will not open.
The other could be the overall tension of the springs. They may need to be
tightened up to help raise the door. If the closer is doing all the work,
the heavier load of the door will cause it to stop. Again, a sensitive
closer will notice. Over time, the springs lose tension and need to be
tightened. The idea is to be able to open the door midway unattached to the
closer and it shouldn't fall nor go up. That's a sign of good tension on the
It could also be the rollers or something within the tracks. If it detects a
slight bump or tug, it will stop. Also check the hinges and make sure all
are fastened tightly and pivoting properly. In time, they need to be
retightened and everything needs to be lubricated.
Also check the screw and make sure nothing is in it's path or check for a
Hope some of this helps.