What should I check if the welding wire stops advancing during welding?

Check the following in order: straighten the torch cable, adjust the drive roller pressure, verify you have the correct drive roller groove size, check the hub tension, ensure the wire is in the correct groove, replace the contact tip if blocked, clean or replace the input guide or liner if clogged, replace broken or worn pressure roller bearings, check torch trigger connections, remove any obstructions in the drive assembly and liner, and release the trigger to reset protection circuits.