When you have finished drawing, make sure that the gutta dispenser is left sitting on its end so that the gutta will drip away from the nib. Have the wire inserted into the nib at all times that the gutta is not being used. Remove the nib and place your gutta dispenser upside down in the opening of the larger bottle of gutta that you use. Let it fully finish dripping. Give it a couple of taps and squeezes to make sure all that will come out has indeed come out.
If you get a buildup of gutta in the dispenser and it hardens, I use a dentist’s scraping tool (I asked my dentist if he had an old one I could have) to scrape the gutta into balls and drag it out of the dispenser. This is a long and tedious exercise, but only once have I had to give up and throw the dispenser out and get a new one.