Hi,
This is an old post, but I discovered a new fix for this continuing problem for any Serenity/Libero/Unity owners with the retractable screen door. Like others, I am used to using two hands to lever the screen away from it's catches, then LET GO, and let it retract itself (sometimes slowly). If you push the screen open, it's asking for trouble, since you will be moving it faster than the drum can retract it. Cleaning the tracks is mandatory but I just found another DIY guide that tells you how to increase the winding tension on the retraction drum.
At least on the original Freedom II body (hard shell molded stairs and door surround) you need to unscrew and remove both the upper and lower tracks before being able to remove the screen cassette assembly. Then you can unclip the entire screen cassette assembly from the wall using a flat screwdriver to spring open the wallclips. Then take the entire drum/cassette over to a table (I did this at a campsite, so used the picnic table). On either end of the drum, there is a single screw holding in an end plate. Choose either end and remove the screw, then gently/carefully pull the end plate away from the screen drum housing. This end plate is wound up with a spring so if you pull it too far, I can't tell you what will happen, but it will probably involve a lot of sweat, swearing and several drinks of your choice. You only need to pull it out about an inch/ 2cm to get the locking pin out of the upper housing. Then you can wind the end plate a few times more ( I wound it about 5 times) whatever direction is against the spring tension. Then put the end plate back in, being careful to align the locking pin with its matching groove in the housing. Then put the screw in and try the screen retraction while still on the table. You can repeat to increase or decrease the tension. Reinstall the cassette and the upper and lower tracks.
My wife gave the thumbs up that this made the screen far more usable. Even if there's a bit more tension when pushing the lead bar against the door-close catches, the benefit is that tension causes the screen to retract more quickly during opening, reducing the temptation to push it, which invariably cocks the leading bar sideways.
Or see this Larson video (slightly different than ours, but same concept)
https://www.youtube.com/watch?v=k3yJXXBBoJU Good Luck
Gary
Shawnigan Lake BC
2008 Libero