If you are having issues with the wire after a weld is complete either being too short or too long you may need to adjust the burn-back settings on the wire feeder. From the Miller S-74 MPa Plus manual:
Burnback (B.BAK) − Burnback sets a time from 0 to 0.25 seconds in increments of 0.01 seconds. This is the time that the arc is allowed to stay on after the wire stops feeding.
Follow along in the video to see how to adjust this setting or use the Steps to Adjust below
Steps to Adjust
To enter the setup menu, press and release the SETUP button (6) on the front panel of the feeder
Rotate the LEFT ADJUST KNOB (3) to select the menu B.BAK in the LEFT DISPLAY (1)
Rotate the RIGHT ADJUST KNOB (4) to select the new time in the RIGHT DISPLAY (2), shorter time creates a longer wire, longer time a shorter wire.