Today I received an old Parker T1 Mechanical Pencil. I do not know how to put refill it with lead pin (or pins). I do not want to learn by trial and error because if I spoil it while trying it will be difficult to make it alright. Also getting another one of this pencil may be difficult. So my request is if someone who has used/using Parker T1 Mechanical Pencil may please advise me on the procedure of refilling. Thank in advance to whever helps with advice.