I don't have a SB, but here are a few things to check:
1. Are you sure it's the SB and not the cartos. If you noticed this with a new batch of cartos, it's probably the cartos. If this happened with cartos that had been working fine, and the draw suddenly changed, it's probably the SB.
If it's the SB,
2. Inspect the SB connector for any obvious damage or obstruction of the indents that allow air flow. Give it a good cleaning with isopropyl alcohol. This probably isn't the problem, but it only takes a minute to check.
3. The battery post may have been pushed in, and as a result, you are screwing the carto in further than you did before. This can reduce airflow. Try backing off the carto a quarter turn or better yet, use a 510 to 510 adapter (assuming it's a 510) if you have one. I'm not familiar with the SB's construction, so I can't suggest a fix. If this seems to be the problem hopefully someone can offer a suggestion here, or contact AltSmoke. They have a very good reputation.