Here is one of the issue that can happen when printing TPU using AMS.
Note that I did not unassemble it to remove the filament, when this happen, you can remove the filament without unassemble anything, just pull hard the filament on both side to make it more “flat”, and then remove it by pulling it from the spool side. I unassembled it without removing the filament to understand what was hapening and where it was happening.
When this happen, it become impossible the filament can be pushed out by the motor of the AMS, or even pulled back, and it stay stuck, by releasing the pressure of the spring a little it is a little better as the gear slip rather than bending the filament but as it then eat the filament this is not ideal either.
Despite what the picture is showing I suppose that the bending happen between the four hall sensors and the motor gear, not after, there is not enough space after the gear to enable the filament to bend like this.
EDIT:
Not sure but I think that at some point the spool feader go faster or push filament more hard than the AMS ouput motor does, and then it bend the filament in the space just after the hall sensors.
I wonder if that removing the motor to let the gear turn freely and to keep the speed meter active can works if the PTFE length is keep short enough, but I am tired to unassemble this thing 
If you plan to do so, be aware that you will need some M2 screews, some are shorters than the original design was targetting for and will become loose
Here are the new ones (wich go all the way trough) I used side by side with the old ones used by Bambulab
