FFCP, need help with filament jamming

Hi
I have been printing with this Flashforge Creator Pro for a few months now. And I had filament jamming before, I fixed it by cut off the stucked filament in the motor then take out the motor to try flush down the jammed filament by pushing it down sometimes with the help of a small heat gun. Then everything went fine, new filament coming out healthy then I can keep on printing.
But lately It keeps happening more and more, sometimes a few times a day when printing large object. And it really bother me having to keep doing the process over and over.
The thing is after doing the same thing like I said, new filament coming out looking great then it gets jammed again.
I would appreciate it a lot if someone here can give me some explanation and advices to stop my printer from jamming too much.
I heard that changing the little tube inside would help it but then again new filament coming out looking great so it can not be the little tube, cant it?
I use mostly Hatchbox PLA but i have tried lower quality filament. Does it matter?
Please help, I want my baby healthy again.
And thank you for reading this.

It could be the PTFE tube. I have found several times that it builds up a nasty spot about 4-6 mm up from the nozzle. When so, the only option is to replace it. What happens is that it creates a high friction spot with some crap in it. This gets worse as the tube heats up during printing and gets softer.