Targets3D,
This really depends on how you are shooting (your form). In the system I advocate (the National Training System - NTS) You cannot regain back tension once it is lost ( that's the theory anyway). If you are settling in on the eye tooth and the thumb knuckle against the jaw, you are most likely stopping your increase in back tension, which causes the collapse.
Here is the part that is much harder to explain in words than to show in person, AND it will sound like an oxymoron! If you are increasing back pressure correctly ( per the NTS), your string and string hand WILL NOT MOVE on your face, but you will still be INCREASING back pressure. The string and hand do not move but by pulling your shoulders back (OR thinking "sticking my chest out") you will be increasing back tension.
If the string and string hand is moving on your face, you are using your arm to "pull through the shot" not your back.
I'd suggest that you have two issues going on at the same time. First is your struggle with form, and second is your issue with TP. Form can be fixed at the blank bale (NO TARGET!!!!!!!!). TP can be fixed by NOT worrying so much about the results and forgetting your form.
Once again, many ways to skin a cat but this is what works for me and many of my students.