I have a 20 year old Parker with a medium gold nib. It sat empty for 15 years. I used to use Mont Blanc blue and black inks. Now using Noodler's green. When I inked it up it was renamed Skippy...verrry dry. I cleaned it with 10% ammonia, 90% distilled water, afew drops of detergent.
Not great, so I did some minor nib adjustments per Youtube and that helped, but not great yet. I looked at the feed with the nib off...under a microscope... and saw white crystalline deposits, some kind of salts, in the capillary channels on the top side of the feed (the side just under the nib). I soaked an hour in cleaner, poked with a small pin and got most of the superficial stuff out. There are still a few deposits deep in the capillary channel.
Is there anything that might dissolve that? I haven't re-inked yet, and it may be good, but I'd like to get all the salts out before inking again.