HP-41C: The "1" key fails sometimes (weak contact).

[g8241CV]

Suggest you search on De-Oxit cleaner. As a warning/hint research broken posts (a hazard in opening a HP-41), and be careful with ESD controls. No expert, but have learned much here via the forum search, and have had good luck. Need to look up threads on opening up an HP-41.

Example link to get you going on the subject:

https://www.hpmuseum.org/cgi-sys/cgiwrap...ead=217869

No affiliation, but a one-stop info source to consider:
https://www.amazon.com/HP41-Repair-begin...B08JJDW6HM