Vulcan AUW230A Heater "volcanous" Questions

pressure switch replacement I have a old Volcan gas ducted heater furnace, i need to replace the vacuum pressure switch, where do i buy one? thank you Standard Appliance, Appliance parts incorporated,

i have a volcan 240 volts ac only watts 1280 5-83 amps model no. 302a ser. no 21821 licened under letters pat. 238292 i want to know a safe way to remove it out of the wall with out killing my salfe e