I'm trying to get my overflow off my tank to move it down a bit. The problem is, I can't seem to get anything between the box and the glass to scrape the silicone. The thinnest things I've tried are a glass scraper and an exacto knife. I even hit the end of the glass scraper a few times with a hammer to get it in with no luck. Is there anything else I can do to get it off without ruining the box?