Lennox International is the current company- and they stopped making tools a long long time ago- they are one of the biggest HVAC equipment companies out there. Not the same as Lenox with one N, which makes some hand tools, along with saw blades.
A big sheet metal tool house might know about some parts for this, and there are no doubt people who will sharpen the blades.
I am not sure if anybody still makes these- Sheet Metal machinery is not a huge market segment anyway, but I havent seen one of these new in 30 years- and the used ones are not in huge demand- but if you have a local distributor of sheet metal equipment, I would call them and ask what they know.