1st timer, with a new opener/low headroom kit issue. top section gets slammed when closing

Hello to all,
I just joined this forum because I'm at the end of my rope and quite desperate.
I've spent 6 days installing the best opener I could find, into my mother's garage so that she doesn't have to get cold/rained on anymore leaving the house and coming home. She's turning 70 soon and I just want her to be safe.

Anyways,  I had to install a low headroom kit (from Lowwwes model#34128ZCDLG) because the door's top section was hitting the opener's drive belt rail when attempting to open.
This kit allows the top section of the door to go along the track at a slightly lower angle as the door opens.
Everything looked great. I finished the rest of the install and adjusted the opener's opening/closing cycles appropriately.
I hit the button, the door slid smoothly/effortlessly up and along the track and stopped perfectly. I may even have gotten a little teary-eyed at overcoming this great installation challenge.
I hit the button again to close.
The door was pushed nice and smoothly back down the track and everything looked perfect... until the last 4 inches of travel. 
That's when the opener's door arm violently pushed/slammed the top section of the door forward and into the door's frame, with a loud THUD.  Then, as the opener pushed the door through its last 4 inches of travel, that top section was dragged along the door frame, sliding/scraping as the door closed completely.
The issue seems to be that the opener's door arm, when pushing the door closed, pushes that top section "forward", during the last 4" of travel, instead of pushing in a more "downward" direction. This top section moves forward due to the low headroom kit, which acts like a hinge, pushing the section away from the roller/track when the door is almost closed.
Maybe the opener's door bracket needs to be moved up, or down, or maybe the opener's door arm needs to be extended, or retracted, so that the correct angle is achieved when the opener's arm pushes the door closed.

There must be someone else out there that has gone through this same problem.  The door is balanced and everything works fine and its all lubed up and there's nothing catching on anything.

Hi I am a proffesional garage door and opener installer. I thought id give you a few thoughts and tips to maybe fix your issues with your door. So first off your going to want your openers header bracket about an inch to 2 inches above your spring anchor bracket. and with the door fully open you want about 2 inches between the rail and the top of the top section on your door. most of the time this works out to make the rail level and proper clearance for the door. also your gonna want the opener bracket on the door for the arm about level with the rollers for the top of the top section. at this point you should be able to line the curved arm up wit the straight arm and bolt them together so that when the door is closed the arm is just slightly tilty backwards. you do not want the arm to be straight up and down when the door is closed. also if you have low headroom track im assuming you got low head room top fixtures(hinges) for the top section that are flat and just have a spot for the roller. when you put these on have the door closed and stick the roller into the top fixture then into the track. you should then be able to move it up and down against the section. mount it far enough down so it holds the top section firmly against the wall. this should keep it from shifting and possibly slamming shut. also check the spot where your vertical track meet the horizontal tracks. if you rub your finger along the inside of the track on both sides there shouldnt be any sort of bump. if the tracks arent meeting up well you will get what we call railroad effects from the door rolling over the bump. take a hammer and some pliers and try and adjust the track so it has a smooth transition.

You should also cover a few other variables other than instlation problems. 
1. is the door in good working order. Ie does it lift easily and close easily with one hand? even your grandma should be able to open and close almost any door with one hand. 
2 Does the opener you purchased have a slow start slow stop feature? This allows the opener to start slowly so it not jerking and shoving the door and stop slowly to avoid them slamming closed. the best opener with this feature is a Sommner Direct Drive garage door opener. Not only are they freakin awesome but they are very easy one the doors. 

anyways i hope this helps.