Pioneer CT-F1250,CT-F950

Hello HiFi Haven, I have a few Pioneer CT F1250,950 questions.
What creates the back tension in FF and RW mode?

What creates the back tension in play mode?

What (parts) create the take-up torque in play mode?

How do the reel assemblies effect the torque and back tension?
The SM suggests replacing the reel assemblies if specs can't be met. Any suggestions what wears out in the reel assembly?
Thank you
When calibrating for metal tape on the CT F1250 the cal. trimmer is 33k not 330K per SM. So, you can't peak the test signal and then back it off. It would appear that full on is the setting. These CT - F1250 are really nice sound decks.
With the restoration, reel motor rebuilds, and calibration complete its time to test, The CT F950's are first.
#1 machine reel motor runs in play mode at 7.9VDC when cold but goes up 8.2-8.3vdc and has 70cgm TU torque.
#2 Reel motor runs at 8.2vdc at start and goes to 8.7vdc and has 40cgm of TU torque.
Seems the motor voltage is related to the TU torque.
Both decks play well and sound great. The sound is more detailed now than it was before the trimmer replacement and calibration. Output, play and play eq trimmers replaced. The transports work well with maybe RW (depending on the tape) can start off a little slow.
One prerecorded tape (so far) wouldn't play (both machines) but it appears to be the tape/ I baked it in a food dehydrator and plays fine in both machines (for now). I will continue to break in the machines then try recording with them.