In 1985(?) Twin States Railroad leased the B&M lines from Woodsville, NH to Berlin, NH & Groveton, NH and the MEC line from St. Johnsbury, Vt to Whitefield, NH (someone a long time ago said it was actually to Fabyan Station in Brettonwoods but I haven't been able to confirm that), at which point Guilford operations ended. To my knowledge Groveton became the base of operations before it was moved to Whitefield. I don't know when the trains between Whitefield and Groveton stopped but I know Berlin to Woodsville, ended in August 1994. Whitefield down to Littleton ended in March/April 1998. Twin States Railroad ceased operations in September 1999 but by then the only section they were operating was St. Johnsbury, VT to Whitefield, NH. I don't believe they were still going to Groveton at that time. Then in 2001 NHCR came into the picture as was pointed out with the link.
It takes real skill to choke on air, fall up the stairs and trip over nothing. I have those skills.