Had the same problem with my frig FGUS2642LF2 flapper door, after cleaning and reapplying grease to no avail then trying to reduce the pressure on the locking mechanisms rod didn’t work either. The solenoid works off of a single electrical pulse to latch open and second pulse to disengage the lock to close after removing the container from the dispenser. After removing the dispenser for a third time I noticed how much spring tension the flapper door had, the door has 2 springs located on each side of it’s axis points. I removed the one closest to the solenoid and noticed the other spring had enough power to close the door. Reinstalled the dispenser and it works just fine now.