Look under neath the sled above the track see if you can see the bolts. If so you going to have to try and and get a vise grips on them or a flat head screw driver to get the bolt to stop turning so you can get the nutt off all the way. Most time you just have to push up on the bolt tight to the tunnel so it doesnt spin depending if it damage or not.
It looks like the T bolt is sitting just inside of the seat on top of the frame and just goes through the hole to where you can see it underneath the sled above the track. So are you saying that there is a metal piece inside of the seat, that if you push up on the T bolt that it will hold it in place so you can get the nut off?
A lort of the time, those bolts are spot welded to a plate inside the seat and the welds break and they just spin.
1992 Ski Doo Mach 1 (SC-10/2 suspended) March '07 SF.com Sled of the Month! (Lost in fire 4-7-13) 2009 Ski Doo MXZ 500SS TnT
2006 Ski Doo MXZ 500SS
1999 Ski Doo MXZ600 Webmaster Evergreen Valley Snowmobile Club SledNH.com Moderator