Hi Sue, unfortunately, if the covering is already coming away from the surface than a repair may not be possible and you may need to replace the feet. Unless the surface is relatively undamaged, then you may be able to repair with a strong adhesive.
To prevent the problem re-occurring you could elevate the feet slightly with rubber or plastic pads to ensure they are never in direct contact with a wet surface (search amazon for 'furniture risers'). The coating can also be further protected by applying two or three coats of clear exterior varnish.