This can be that you need a goo cleaning of the toaster. It is possible that Bread crumps and toasted crumps has hardened and got deposited on the tracks of the hinges and carriage.
So you will need to remove the unit and see the tracks of the carriage to which it moves.
Clean the portions with some edible oil and dry wipe them off.
Make sure in this process that the carriage is manually moved for free movement.