Another way to help loosen track tension after you take the check loose is to back up with a piece of firewood between the track and the sprocket just take it slow
This is how I loosen up the tracks on my rubber tracked crawlers to replace them. I used a piece of 4x4 and walked it between the track and the sprocket. It worked like a a charm. I tried every other which way to move them including come-alongs and pushing with another machine with no luck.