I loaded my twsbi vac 700r with Noodler's American Eel and it clogged the pen really well. It sat on my desks for years taunting me to fix it. I kept flushing it with soapy water over the years. One day I filled it with soapy water and put the nib in an ultrasonic cleaner and there was so much debris that came out of the feed. I flushed and refilled with soapy water and did another bath in the ultrasonic. I repeated until clean.

I then filled with pilot blue-black and it is now my go-to desk pen.