A gearbox failure is serious business. They will have to remove the bull wheel to replace/repair that. I honestly think that's pathetic. A Chairlift gearbox is a very simple worm gear and ring gear and can be visually inspected without too much hassle. It should be evaluated frequently. It should also have some sort of temperature monitoring device as well as an oil level monitoring device.
The gearbox on the triple at Plattekill started to wear a bit a couple years ago and they sent the gears out to be hard faced and re-machined.
If they have that quad down for a while, it's going to be a shit show over there.
I'll take boilerplate ice over wet snow any day