Hi Gary,
Was the Ignition Switch a "like for like" replacement ?
The early 250 cars did not have an "accessory" position on the switch, and that can cause a problem if later type parts have been fitted.
My early Ignition Key Mechanical switch wore out & fell to bits, last year, and a newer type was used to replace it, by the garage I use, and since then the parking lights do not function correctly - they operate when ignition is off, but not when key is removed.
I suspect there is some rotational displacement between an Early electrical and Later mechanical assembly
It is a non urgent job for me to look at sometime....
Interested to know what you find
Paul