Got a vintage ALPS plotter? Two things you need to know.
1. The X/Y gears on the motor spindle are likely cracked. I had 3D printed versions available at Shapeways. Maybe they'll be available again soon? There's also brass ones too.
2. Pens are likely still available from Best Electronics in California. They have black and 4 color sets. They're NOS so it's a roll of the dice how long they'll work. Search for Atari 1020 pens.