When I bought my first 61, the seller said to flush it by sticking it under the tap, nib down, and let water run through the capillary filler from the back. I have hard water so instead I used a bulb syringe and distilled water. I ended up using the pen for something like four MONTHS -- just on what the reconstituted ink came out when I started flushing it. When the pen would go dry, I'd flush it till I got ink coming out from the nib. Then, when it got to the point of being so diluted as to be illegible, I flushed out really well.
Be prepared to use an ink that isn't overly saturated (J Herbin and some De Atramentis standard inks have worked for me). And be prepared to use an ink that you really like the color of -- because capillary-fill 61s hold a HUGE amount of ink.... I wasn't kidding about the four months part -- it was about the same with my second 61, and I'm now running into something similar with the third one, I bought last fall at the Ohio Pen Show.
Ruth Morrisson aka inkstainedruth
ETA: Congratulations. The pen looks lovely (none of mine have fancy caps). And the fact that it's a family heirloom just makes it even more special.
Edited by inkstainedruth, 04 March 2018 - 05:42.