If you're experiencing slack in the web while running or immediately after splicing in splicer defects, there could be several causes. One possible cause is paper roll over traveling, which can occur due to insufficient braking force. There are several factors that can contribute to this issue, including low air pressure, worn chucks, worn brakes, a bad roll, or automatic tension control not functioning as designed.

To address this issue, it's important to check the braking force and ensure that it's sufficient to prevent paper roll over traveling. This may involve checking the air pressure, inspecting the chucks and brakes for wear and tear, and replacing any faulty components as needed. Additionally, it's important to ensure that the automatic tension control is functioning properly and making adjustments as needed to maintain the proper tension in the web.

By identifying and addressing these issues, you can prevent slack in the web while running or after splicing, ensuring a smooth and efficient splicing process.