Stop early, back the drive off if you can, re-square the duct, check for bent hems, then restart the drive straight. Fix the mechanical fit before sealing.
Stop early and fix the alignment. A crooked drive usually means the duct is twisted, unsupported, damaged, or not fully seated.
Do not keep driving it until the corner folds or the duct oil-cans.
Check
Stop driving the moment you notice it going crooked - the further it goes in crooked, the harder it is to back out without damaging the hem.
Back the drive out by tapping the exposed end backwards with your hammer. Work evenly side to side - do not pry or wrench it.
Once backed out, check the hem on both duct ends for bends or deformation that would cause it to run crooked again.
Check that the S-cleat is fully and evenly seated on both sides before restarting the drive.
Restart the drive square: start the leading edge of the drive evenly on both the top and bottom hem before hammering it across.
If the hem is damaged and will not let the drive start square, the S or drive may need to be replaced before proceeding.
Steps
Stop driving the moment you notice it going crooked - the further it goes in crooked, the harder it is to back out without damaging the hem.
Back the drive out by tapping the exposed end backwards with your hammer. Work evenly side to side - do not pry or wrench it.
Once backed out, check the hem on both duct ends for bends or deformation that would cause it to run crooked again.
Check that the S-cleat is fully and evenly seated on both sides before restarting the drive.
Restart the drive square: start the leading edge of the drive evenly on both the top and bottom hem before hammering it across.
If the hem is damaged and will not let the drive start square, the S or drive may need to be replaced before proceeding.
Say this to your foreman
My drive cleat went on crooked and I backed it out. The hem [looks okay / looks bent at ]. Do you want me to replace the drive/S and redo it, or is there a correction I should make first?