A question from a Duofold User ...

[Udo]

[Heinkle]

The famous auction site typically has strange spare parts like finial caps, NOS barrels and blind caps, but unsurprisingly your best options are to take good care of the pen and (in extremis) buy a second as a donor, although this won’t be cheap.

 

Without doubt the hardest part of the pen to preserve is the gold plating around the base of the nib - so many Centennials and Internationals from the 80s and 90s have fallen victim to corrosion. In such cases you’ll need to track down a good condition Mk1 nib, which I suspect will gradually get harder to do.

 

Lovely Mk1 Big Red though.

[Udo]

Thank you for the information. For what reason do the springs corrode? Is it related to the ink used? I only use Pelikan 4001 or Parker Quink ink in the pen.

[Heinkle]

As I understand, it is a combination of very thin gold plating on the nib rings and the acidity of ink that causes the corrosion. 
 

I think the general consensus it to ensure that any ink is carefully wiped off the nib rings as soon as filling is complete, especially before capping the pen. Alternatively, you could use a converter snorkel that allows you to bypass the nib:

 

https://www.purepens.co.uk/products/pineider-snorkel-filler