Its possible that the feed channel is partially occluded. First you could try soaking the nib in water or water mixed with dilute ammonia for an hour or two and then try flushing it out with water. If this does not help its possible the feed channel must have some kind of undissovable debris in it. If that is the case, try following the advice in this thread, or this thread using a .009 inch thick guitar wire string, fitting it into the hole in the back of the nib and then allowing it to feed out the front. If there is ink debris, you will feel a bit of resistance, but if you are patient, and gentle you can get the nib all the way thru and then see little ink particles flushing out finally with water. The nib should write more wet after this. I've personally done this several times on old crusty esterbrook nibs and it works great. Good luck.
Edit to add,
after ammonia step and before the guitar string step, and you don't mind spending a few extra dollars, you could invest in rapid-o-ease cleaner and ear bulb and soak nib in it and flush it. You could also get an ultrasound unit which works well on these nibs too.
However if you want to go the cheap route, then the best way to go is a good dilute ammonia soak, and flush, followed by the steel guitar string (its the smallest string on a guitar and you only need to cut a two inch piece off it for this purpose).
I've used twist ties as well but you need to remove the paper off the twist tie and they bend more easily than the guitar string which works the best.
Let us know how things turn out, ok?