Cannot change parameter 340/341 - Pega 357 04P-C

Hi all
Had an issue with an accidental memory wipe (DO NOT hold zero/delete whilst powering on! in a bid to clear alarm "memory clear required")
Thankfully, had the sense to create a backup tape file (machine.t and pc.t) so do have access to all the parameters. I'm able to set PWE to 1 and change almost every parameter manually, however the 2 that set the input and output device will NOT change. Tried from the SETUP page with not change and also from parameters 340 and 341 (which I read on this forum).
Is there an access level I need to unlock??

Just to add, I'm using a program called Code Shark. Although the backup was done using Code Shark, and I can open the .T file, nothing appears on the screen. If I open it in notepad, all the P and N data is there.
What do you guys use to transfer the .T file back to the 04P-C ?

Slow progress - I entered parameters N000 through N0010 as well as N0300 through N0312
This somehow allowed me to access and change N0340 (INPUT) and N0341) OUTPUT.
Once I did this, set the machine into READ mode (SETUP, > button, then P-9999 READ)
With the READ flashing, I sent the backup file and all appeared to have gone in - there were 7 blocks not sent.
I not get alarms:

240 +C OT
417 X SERVO DGTL PARAMETER
427 Y SERVO DGTL PARAMETER
447 C SERVO DGTL PARAMETER

Have double checked 8100-8124 (X-axis), 82xx (Y-axis) and 83xx (Z-axis)
I assume 84xx is for the C axis but not sure

Any ideas?