A few favorite ball-point pens that I haven’t used in a long time have “dried out.” They are still filled with ink, but their tips refuse to write. The little ball, I assume, is glued in its little socket by caked ink. I’ve tried pressing hard while scribbling furiously. I’ve tried soaking the tips in, first, diluted dish detergent, and then, rubbing alcohol. No luck yet.
Any ideas to rejuvinate them?
Heat the tip of the pen with a lighter, and try scribbling again while it’s still hot. (All with due care, of course)
A somewhat less drastic approach is to soak the tip in a shot of vodka for 20 minutes or so.
I always find the lighter method helpful.
This method may turn your tongue blue.
what? why waste a perfectly good shot of vodka?
Just to counterpoint the lighter method - I used to use it all the time, and it does usually work. However, the last time I tried it, the ball actually popped out of the pen, hit my curtains, leaving a beautiful blue streak, and ink flowed copiously out of the now balless tip onto my jeans.
Never bothered trying that again. And just for clarity - I’d held the lighter to the tip for maybe 5 seconds.
You don’t need to use vodka to do it. Rubbing alcohol will work too (just don’t blame me if that little blue glass causes severe gastric disturbances afterwards)
If you use a lighter, you only need to do it for 2 seconds or so. Write with it immediately following.
Sometimes this will work for me, but not always. Put a drop of water on a piece of plastic (or anything that won’t absorb it) and spread it out. Now write on this surface for a while. If you are lucky, the water will rewet the ink. Every once in a while, switch to a piece of paper to get any rehydrated ink off, then back to the wet surface again.
I don’t mess around with trying to rejuvenate the pens. I just get a new refill and that works best for me.
In Soviet Russia, pen cleans you!
I used to soak them in hot water for a while. sometimes it works.
Now a days I just throw the damned thing away.
A lot of the parts around the ball are plastic these days and will melt and deform if heated more than a second or two.
You’re supposed to <i>warm</i> the tip of the pen with the lighter, not make it boil. 
I just toss them now too. I have more free hotel pens than I could probably use in a lifetime. I remember as a kid I would write on rubber, specifically the underside of one of my sneakers, which would get the pen going sometimes.