Broken Progress, advice needed

Gents, looking for some advice related to one technical issue with my beloved Progress.
After 2 years of use (around 2 times per week) I noticed that the thread of the top cap started to shred, leaving the zamak exposed. I have the feeling that little by little the top cap will be compromised - if not already.

Initially, I thougt I might use the top cap from my mint vintage Progress 800, but the thread is too short, unfortunately.
I was stunned by the quality of of the manufacture, miles ahead from what you discover under the top cap of the contemporary Progress.

Now, before spending 65euros on a new Progress and maybe ending with the same quality of the top cap, I will look for alternatives and here are my thoughts:

Can someone who owns both a Progress (short handle) and Parker Variant tell me of the top cap is interchangeable?
Also about the quality of the thread in Variant ?

I would look for ways to add a small extension to the Progress 800 cap - 1 cm screw with the same external thread on one side and the other on the inside (don’t know how it is called in technical terms) but don’t know where to look for that. A brass manufacturer would be ideal but again, rare to find.

All advice is welcome!


Forum GOD!
Have you tried emailing Merkur customer services? They sent me a replacement part for a 70 year old slant free of charge and apologised profusely for the failure, I nearly fell off my chair!
Sounds like good customer service you received.
I wish it were more common.