Hi, Welcome to JustAnswer.com, I am glad you are here! My name is Eric & I will endeavor to answer your question.
The reason your door is reversing itself is because it is sensing resistance. When you "Help" it, your "Help" overcomes the resistance and he door functions normally. As doors age and things settle, sometimes what was a new free flowing mechanical device over time, doesn't "free flow" as well as it used to when new. This is expected. Here is how to overcome that issue...
Up on the motor should be 2 dials. Sometimes these are just a shaft about 1/4" in diameter sticking out of the back with a slot for a screwdriver and sometimes you have to insert a small screwdriver into a hole. There should be some type of directional indicator telling you which is more and which is less.
These are upward and downward force adjustments. Increasing the downward force slightly will tell the system to push through a greater resistance in the down direction. Increasing the upward force slightly will tell the system to push through a greater resistance in the up direction.
Try increasing the upward force just a little. If that does not solve the problem, try increasing it some more.
It would also be a good idea to have a helper watch the rollers and tracks carefully as you are working the door to see if there is southing that might be impeding the doors free movement which might be visible.
Also, lubricate all of your rollers. Use a silicone spray. Don't spray where they roll in the track but rather into their axles. Please let me know if this helps you solve your problem.