When I lost mine I put a 10gal on the ground w/ a undertank heater on, but no light, and a hopper mouse in it, and I made it so that the snake could get in but the mouse couldent get out. Then I had the hides set up so that maybe hed go there after eating. It took a week, but it work. And also if theres any washers/dryers down there, check under and behind them and same w/ hot water heaters. They love em.
And Id also suggest putting flour around everything too, maybe not directly where you walk, but everywhere else. That worked great for me, too.