Engineer wrote in :

Results, all good:
-- took off end caps, very clean inside, no rust
-- freed-up armature by hand, moved easily, not stuck
-- removed bearing end plates, bearing grease looked a bit congealed,
added some "electric motor" oil to thin it a bit
-- commutator and brushes in perfect shape - factory new, of course
(there are several new brushes in small metal cans actually stored in
each end of the dynamotor - great idea!)
-- powered it up unloaded on var. DC supply, it started to turn at
below 12 VDC (I did not record the exact value), ran it up to 28 VDC,
about 262 VDC open circuit on the B+ supply line
-- added 10 Kohm load to B+ line, 255 VDC loaded (~ 25 mA DC)
-- ran unit for 1/2 hour to mix the bearing lube and polish
commutators/brushes
-- unit now starts to turn at 2.6 VDC (unloaded)
-- reassembled and put back in chassis pending radio test.

Correction: title error. It's not "280 VDC", it's "230 VDC" (I read
the label wrongly)

Pretty good after 65 years on the shelf. Prognosis for band-switch
motor now seems good! But not looked at yet.

That's very good news.

Can I touch you? Maybe some of that incredible good luck will rub off.

--
Mike Andrews, W5EGO

Tired old sysadmin