I don’t even know if a secondary clutch is a thing, but I recently got 2 older Tombow pencils that are experiencing the same problem.
(I was able to fix one of them, but the other is being stubborn.)
Problem goes like this:
Clicking to advance the lead pushes lead out, but then the lead immediately retracts the exact same amount (so no lead is actually advanced).
If I use a piece of lead short enough, the lead advance works. Once the lead is long enough, it hits something up inside the clutch that’s really grabbing it and not letting go
How can I clean up or de-gunk whatever is up inside the clutch that’s grabbing the lead? Is there a secondary clutch in there? I’ve not encountered this before and am not sure what to do to fix the issue.
Secondary clutch like in the lead maximizer designs? Could it be a “returns” system where short half click advances lead and long full click retracts lead?
I knew I’d throw off the scent with my uninformed use of language.
I dunno what the hell it’s called, but something behind the visible clutch is grabbing the lead harder than the clutch itself. I have no idea what this piece or thing might be. (It’s nearly 1cm past the clutch itself.)
I suspect the problem is rust and age after 50+ years being stored in old stationery stores. The clutch works but the rubber retainer nub might have dried and cracked, failing to hold on to the tip of the lead. The ‘mid-upper’ parts of the clutch that are supposed to slip back over the lead have some rust build up and results in pulling the lead back into the reservoir, as there is no countering force from a working nub.
This has happened to some of my slide-pipe pencils from Tombow and Sakura. Best remedy so far is to use a cleaning pin and hard scrape the innards of the clutch.