Bush Hog blades question

[Mudball]

I recently purchased a Bush Hog SQ600 that been sitting for maybe a year or so.
Since I bought the unit I ran it in some small saplings, 1" vines and some thick briars for around 15 to 20 minutes. I then parked it and checked the blades and they are very tight against the stump jumper. I cant move them with my hands but I did not try hitting the back side of the blade with a mini-sledge and thought I would ask first. I thought they would have been freed up by now. They still do move freely on a shouldered bolt dont they ?
Im thinking of removing nuts, bolts and see if the bolts are the correct length, clean if need ? IDK

 

[jim043]

Could be brush or other material between the blades and stump jumper.

 

[Diydave]

flip it up on its side, and take a look, it could just be bark, briars or even a piece of wire trapped up near the bolts, and blade...

 

[Mudball]

Could be brush or other material between the blades and stump jumper.

flip it up on its side, and take a look, it could just be bark, briars or even a piece of wire trapped up near the bolts, and blade...

Thanks for the help. I now have the unit disconnected sitting on blocks. I did look at the "like new" blades and all around the swivel bolt area and they are clean as a whistle. I guess it must be rust and the blades havent hit anything solid enough to break them free.
I will penetrate spray and leave awhile then later hammer tap to the back side of the blades to see if they move.