I got a used 907 on eBay, thinking it was genuine, but now not sure. It has an additional close fitting sleeve over the element, which can freely slide up and down, doesn't attach to anything, very slight flare at one end. I don't see it in the parts list. Any idea if this "extra" should be there, or where it might have come from? Seems like it belongs, just not attached.
Sounds like the inner sleeve of the irons tip .
Once the tip gets old it tends to expand /fatten up and the inner sleeve just slides out/ stays on the element.
The tip is copper an the sleeve is steel.
This expansion of the barrel causes the tip to run cooler than you suspect cause it is not in direct contact with the element anymore
You can just buy a new tip they're cheap.
However, I've been able to reshaped mine for a spare by creating a die about an inch long, with the right size hole with the right size wall thickness by cutting a slot along the length in it for expansion so it can bend flex to accept the wider barrel and not get completely stuck .
I then push the tip with a little lube though a press or vise with the right size spacers rtc. to re compress the barrel of the tip to re-grab the sleeve.
Takes a couple passes and 2 minutes, of coarse, the die bit took longer to fine in the bin of old junk and cut a slit in it
I used these tips for less than delicate work where i don't care and just need some heat
Ah! I wondered if that might be the case, but not knowing how the tips are constructed had no way of knowing if it was, if you get my drift! I have lots of tips anyway, this must have come from the tip that's on the iron since it's fairly loose.
I like your method of refurbishment!