I have model v2244 and it has been working normally until it was used today. Normally you place a bag in and lock it then hit the vac/seal button and it vacuums to a point when all the air is gone it will then seal. But today ever time I did that it would just keep vacuuming even though all the air was gone. It seems the sensor that normally says hey I'm done vacuuming time to seal is not working I had to let it vacuum then hit the seal button. What should I do?