On my 9303 my current settings are as follows:

1. THRO: H100% L95%
2. Failsafe: THR set to F.S.
3. Pos. -256
4. Subtrim: 0
5. Rev.SW: THR Norm
6. Device Select, Trim Step: 40%

To get the Pos -256, set the travel adjust (TRVL ADJ.) for low throttle to like 150% with the throttle trim at neutral. With the throttle stick at low idle go to the Failsafe menu and set failsafe (F.S.), then press the memory button. When you get the large negative number, go back and readjust the throttle percentages hi and low. Next, try to do Learn R/C with the ECU and then check for failsafe by powering off the Tx. Good luck...

Ken