The ARPrv.com website
explains everything perfectly. The factory "fix" is a small black box attached to a boiler tube.
It has a tiny red LED that lights when it has tripped, but nothing telling what it is on the box. By the time it trips out the entire cooling piping has been subjected to overtemperature. The cooling system has an overtemperature "blowout" plug to release excess pressure and prevent it from rupturing; thus the one-time use.
Personally, I will not use a magnet to reset my Norcold factory recall "fix". When/if it trips I'll just contact our extended service contract and have it replaced after it has been properly diagnosed by a repair shop. Since my deductible is only $100+ diagnostic charge, I think I have the proper solution.
FWIW, I think the ARP presentation of normal boiler temperature is too high. I prefer to believe the mechanical engineer and professional fire investigators who authored the second link.
2000 Winnebago Ultimate Freedom USQ40JD
, ISC 8.3 Cummins 350, Spartan MM Chassis. USA 1SG, retired;PPA,Good Sam Life member."We the people are the rightful masters of both the Congress and the Courts - not to overthrow the Constitution but to overthrow men who pervert theConstitution. "Abraham Lincoln"