Dont know of any in Maine, but Granite State Power Equipment in Pittsburg NH does. I just bought a 2013 XF1100 T Crosstour from them this past weekend. They did the jackshaft & Bearings, secondary clutch and a few other things to it. Family has used them for years, may be worth the drive if you cant find anyone closer.
You might try Performance Edge in Hancock. He specializes on ATV's but he also works on snowsleds. He is not afraid to work on anything, btw. Has worked on my Arctic Cat "Turbo Diesel", most dealers would be clueless.