Items that are necessary to fix a loose or unstable toilet seat include rubber bushings and seat stabilizers, which are found in a toilet seat tightening kit and a toilet seat stabilizer kit. Additional tools and materials that are required are a 4-in-1 screwdriver, a drill, drill bits and pliers.
From the tightening kit, remove the rubber bushings, and install them onto the toilet seat with the tapered side facing up towards the seat. With the provided tightening tool, securely bind the nut. For a more permanent fix, completely remove the nuts in the toilet seat, and replace them with rubber bushings. As of 2016, toilet seat tightening kits are sold at home repair stores for around $3.
To install a toilet seat stabilizer, wrap the rubber band provided in the stabilizer kit around the toilet seat, centering the stabilizers. The stabilizers should touch the inner rim of the toilet bowl. Drill a hole into the stabilizers, and then screw them down with a screw driver, using the screws provided in the kit. Toilet seat stabilizer kits can be found at most home improvement stores for around $4. After installing both the rubber bushings and stabilizers, check how secure the seat is by attempting to wiggle the seat back and forth.