ISSUE: The sealing line is not complete.
SOLUTION: Check to see if the heat-resistant cloth is damaged and replace if needed.

ISSUE: Poor sealing on bag mouth.
SOLUTION: Check to see if the heating wire is damaged or burned and replace if needed.

ISSUE: Machine is not pulling enough vacuum.
SOLUTION 1: Check to see if there is enough vacuum pump oil in machine and fill if needed.
SOLUTION 2: Check the oil quality in machine and replace the oil with new, clean oil if needed.
SOLUTION 3: Check the rubber gasket and replace it with a new one if it is damaged.