Check my trail conditions report for Carlo and Goose Eye that I posted just this morning. Follow the directions to the log yard. You'll be on Hutchins Street.
There is a landfill on the right side of the road, then a phony-looking hill that is probably the former landfill. (On our initial pass, I noticed the hill, but drove right by it.) There's an unmarked dirt road just past the fence that's in front of this hill; that's Success Pond Road. I believe there was a street sign on the left side of the road that said "Hutchins St. Ext." If you get as far as Bridge Street or Myrtle Street, you've gone too far.
Reset the trip counter on your car's odometer to zero; the Carlo Col Trail head is 8.1 miles along. There are a couple ruts leading up to the right, with spaces for a few cars up there.
Be careful driving along Success Pond Road. There was no activity when we went there a couple Sundays ago, but when we returned on Tuesday we had to wait a couple times while workers made room for us to get by. One particularly frightening machine was picking up trees and jerking them back and forth to strip the branches off them. A big counterweight, or whatever it was, was right over the road, and if I'd tried to sneak by, it probably would have bashed in the roof of my car. I just waited a minute or two until the worker noticed me; he turned his machine and waved me past.
The road is in decent enough shape, but it was still wearying driving it. Tuesday we went to the Speck Pond Trail head—a big open area on the left side of the road, then followed Success Pond Road to York Pond Road and out to Route 26 near the upper end of Grafton Notch.