Insert the Ramrod into the muzzle.
Prime:
Firmly, but gently, push down until you hear a faint click as the plunger locks back.
Remove the Ramrod and drop a dart or Rival ball down the muzzle.
Use the Ramrod to gently push the dart or ball down until you feel slight resistance.
For a dart, do not push the Ramrod down too far, or you may lose the dart in the Plunger Tube and need to partially disassemble the Musket to remove the dart.
Unjamming instructions are available here: https://docs.google.com/presentation/d/17hclY8uhBb8ab-xeaDNVUEfetOA4go7ZoK41L7WxW6c/edit#slide=id.g172882aec24_0_29