Over time, the microscopic suction pads on the metal rails can wear down, especially if you can't go a day without using the TWA ;). If it's just a matter of dust, it is possible to wipe it with a damp cloth in order to refresh the pads and renew the grip and effectiveness. If that doesn't help, or the pads are already worn down, order this fresh double set (set of 4 pads).
How to install new pads:
Slowly peel the old pads off with your thumb, wipe the metal rails with a cloth using rubbing alcohol, dry, and then apply the new set of pads. Do not remove the clear protective liner on the pads until after the pads are fully installed. Now you can remove the liners on one or both of the pads. Replace as needed.
Tips for longer life:
Leaving your ToneWoodAmp attached for long periods can flatten the pads as they are sandwiched between the magnetic rail and your guitar + X-brace. Removing the ToneWoodAmp periodically is recommended as it relieves any pressure applied to the Suction Pads.
Twisting the ToneWoodAmp when removing will only cause damage to the suction liners. Be sure you are lifting off your ToneWoodAmp from one end and allowing the TWA to separate from your guitar.