Our Sealand toilet's vacuum break started to leak and we learned we have to order a different part than used on recent model Travelers.
In the year of 2000, Sealand stopped supplying some parts for the model with overflow holes.
Our Sealand Traveler toilet's story: Dometic Sealand Traveler 511+ short base toilet (http://beamalarm.com/Documents/dometic_sealand_traveler_511_short_base_toilet.html)