I really enjoy using my old Vibroplex's OTA (usually 40M) and have several oldies dating back to 1914.  It's a lot of fun to speculate on their history and I  always like to think the original owners would be happy they're still making Morse.

I believe  in carefully cleaning them so they don't stick to me and are functional , but not much beyond that.  I'm working on a 1920 VIbroplex that was apparently owned by a heavy smoker. I'm removing the slimy sticky mess with warm water, cloths and mild soap.  It'll be cleaner but always look like a 101 yr old instrument, which suits me. This slow cleaning gives me an opportunity to inspect the parts carefully.

One thing I've noticed is that there's often a variety of knurling on the various hardware.  While I know that rope knurls were usually used, several of my older keys have a variety of rope, diamond and straight cut knurls on the hardware.  I'm guessing that this mixture  comes from owners making "field replacements" of missing pieces rather than Vibroplex mixing their hardware manufacture process (I'm also guessing they built, not bought their components) .

Does anyone know ? I suppose the supply of NIB century-old Vibroplexes is pretty low to check for sure, but it's fun to speculate.

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John K5MO