Hi Eddie
Thank you.
I may have solved it.
Initially I just updated FS20 & FS24 though Inimanager & got the result expounded above.
So I went back & uninstalled the FS24 F406 & fully reinstalled it & took another flight into KBOS Rwy 33L, & this time the LOC green light came on!
I tried an ILS into 33L & it was going per plan then I fiddled with "Approaches" in the PMS50 650 GPS & things went somewhat awry.
On reflection I think if I leave the GPS subtleties alone & just run an ILS through the AP, I suspect it will work.
So rather than having your people chase this one, could I suggest that somewhere in your instructions you advise us to fully uninstall, then reinstall, the F406 after an update?
It seems to need that for the changes to "take".
A2