G-Man wrote: ↑Tue Jan 14, 2020 4:49 pm
The face looks pretty tired regardless of the stain. Best to pull it apart and find a better face or get an overlay for that one.
G
Let me share another perspective on this.
Opening up these instruments is by its nature destructive. I have successfully repaired several CB77 speedo/tach units but it requires careful prying open the swage and then careful bending it back into place. I have never reopened one of these instruments but given the stress and strain it causes on the chrome band I suspect that two repairs is the maximum that can be done without leaving obvious damage.
If I were preparing a bike for show I would follow Graham's advice simply because nothing but the best is good enough. However, if you are rehabilitating the bike, i.e. not restoring it or showing it competetively, I don't see a problem with signs of age such as this. The bike is, after all, 50 years old and there's no reason it cannot show some signs of this. After all, its mere existence as a usable machine is a significant victory.
So, if the instrument is working and is in reasonable shape I would leave the opening and repair for later, perhaps the next owner, when it might be necessary simply because the number of times it can be repaired is so limited.