steihy

I have acquired one or more of all the brands you mention over the last 6 months, both because of a similar fascination and aided by pretty good availability here in Norway.
The 360 I got was in nice condition except two things. One was a windfall. I got it very cheap because it was "broken", didn't run. All it took was the usual cap-ectomy, removal of the cooked out rf capacitor. In the US that is not an issue, apparently.
The other is more common for machines idle for some time, as this is pretty tight tolerance engineering. Not as notorious as the Necchis, but...
The ZZ movement was frozen, and those links are buried deep in the arm. In order to work them, and to test the action of the regulator cylinder, I took it out. The cylinder was in top shape, and the links freed up nicely with the usual heat/penetrant treatment.
This was months ago. I have since read the service manual to tatters, talked to every Pfaff veteran I could find, and spent many hours trying to fit the cylinder back in. Can't do it. Not saying it can't be done - the active Pfaff mechanics wanted hundreds of dollars to reassemble for me.
I know now that I would have gotten by just removing the embroidery unit and working the links without taking the cylinder out.

Note to self, quote from 120 yo White VS lll manual:

Any unskilled person attempting to adjust or repair any machine will often do greater injury than years of ordinary wear could produce.