You might replace the two SERTXD statements with a single one (replacing the second) like this:
sertxd("Desired/Feedback: ",#desired_pot_value," ",#feedback_pot_value,13,10)
DONE!
Here are the results copied from Notepad
"Feedback" never seems to catch up with "desired" beacause of the "diff" command.
Desired/Feedback: 210 201 is at the end of the range the motor can move.
Desired/Feedback: 210 191
Desired/Feedback: 210 192
Desired/Feedback: 210 192
Desired/Feedback: 210 192
Desired/Feedback: 210 192
Desired/Feedback: 210 192
Desired/Feedback: 210 192
Desired/Feedback: 210 193
Desired/Feedback: 210 193
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 194
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 195
Desired/Feedback: 210 196
Desired/Feedback: 210 196
Desired/Feedback: 210 196
Desired/Feedback: 210 196
Desired/Feedback: 210 196
Desired/Feedback: 210 196
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 197
Desired/Feedback: 210 198
Desired/Feedback: 210 198
Desired/Feedback: 210 198
Desired/Feedback: 210 198
Desired/Feedback: 210 198
Desired/Feedback: 210 198
Desired/Feedback: 210 199
Desired/Feedback: 210 199
Desired/Feedback: 210 200
Desired/Feedback: 210 199
Desired/Feedback: 210 199
Desired/Feedback: 210 200
Desired/Feedback: 210 200
Desired/Feedback: 210 201