Man, that is old, and a giant beast.
Centricut, which is a division of Hypertherm, claims to have consumables for it-
Plasma Cutting Supplies/Parts for ESAB Torches
I would call them and ask, giving them your torch model number. This thing may or may not have the same torch on it now it shipped from the factory with.
here is a link to the factory troubleshooting manual, but its pretty thin.
http://www.esabna.com/literature/Pl...CM-150/PCM-100-150_Maint-Parts_F-14-483-A.pdf
factory manual-
http://www.esabna.com/literature/Pl...PCM-150_Plasmarc Cutting Package_F-14-474.pdf
It looks as if it originally required 2 different gases at the same time- a cutting gas, which the manual says could either be Nitrogen, or H-35, which is a fancy argon/hydrogen mix-
Argon-Hydrogen Mixtures -- Praxair's <I>HydroStar®</I> Gas Blends
and then, it also needs a cooling gas- which can be either C02 or another weird proprietary mix- they spec an Ox/Nit/Air mix.
And it needs LOTs of em. cooling gas wants to run at 340 CFH. (further reading indicates you could use compressed air for cooling gas, but tip selection varies depending on cooling gas and cutting gases used, and material being cut- in other words, to be really flexible, you probably need to stock a few hundred bucks worth of different tips)
The lack of a cooling gas is probably why your base metal heated up and your torch tip melted.
This was a machine cutting power supply, made at a time of big changes in tech, and it was a very complicated, expensive machine. Nowadays, nobody would want something like this for actual machine cutting, its too expensive and complicated to run. Much cheaper easier, simpler, and more reliable power supplies out there now.
I hope you got it really cheap. My guess is you will find it to hard, and expensive, to run, and scrap it.
But good luck.