The Door Balancer
A quick fix in six simple steps!
Step 1:

Wear safety goggles.
Step 2:

Remove the least conspicuous hinge pin.
Step 3:

Open door fully.
Step 4:

From door jamb side, hold one end of spring, tabs down, and use thumb to slide spring over hinge pin hole.
Step 5:

While holding spring, reinstall hinge pin.
Step 6:

Open and close door five times to set spring.