[Craig Sawyers]

The teletype or teleprinter groups have a real problem with WD40. Now these are really complex (much more complex than a record deck) electromechanical assemblies. And of course now full of tarry grease.

If you make the mistake of spraying on WD40, it mobilises the grease and washes it even deeper into the moving parts. The WD solvent then evaporates, and the teletype is now seized solid. The only recovery is complete disassembly (hundreds of parts, springs etc), complete clean and relubricate.

Now I haven't done one of those, but I have restored the BP Lorenz SZ42 from WWII. And I did strip the critical parts, washing them in solvent (IPA or hexane) and used modern greases for precisely that reason.

Then they had a partial SZ42 from a military museum in Norway. The plan was to restore that too, and use a modern motor (that was missing) and do a similar restoration. The Norwegians were having none of that - they viewed the original grease as being "an historical artefact". I kid you not.

Craig