The bolts through the sheaves are there only to keep the structure in place and are not supposed to create pressure on the sheaves. There should be free space and the sheaves are suppised to be free to move upward on the bolt for a mm or so. So maybe someone drew the bolts too tight.
Otherwise, all you need to do is to clean sheaves and bolts with wd40 and or water to remove any matter that foules the movemement. I do not see a need to remove the whole contraption unless the bolts are bent, rather unlikely.
Meir Riba