I'm trying to put back to work a lettera 22 recently purchased. I had hard time unlocking the carriage, as shift keys were blocked and the spacebar plow was stuck preventing the carriage to move. Now the carriage is free and spacebar plow works mechanically back and forth. Nevertheless the carriage doesn't advance and keys movements doesn't seem to engage the escapement. On the other hand, backspace works. Any suggestion on how to tackle this issue?