Hi, been reading with great interest.
One thing worth noting is that the standards changeover will only operate when the set is fully warmed up and operating with current passing through whichever choke is in use.
(Apologies if I'm teaching my grandmother to suck eggs lol.)
I repaired a Decca DR303 (similar if not identical chassis) a while back and here is the restoration....
https://www.radios-tv.co.uk/communit...tandard-dr303/