Hi Mid,
I have just had a quick look at both the Norway Ju52 and the one included with the defualt set of ETO aircraft.
both of these planes use the same effects and weapons, pylons and guns. so there should be no conflict relating to the loadouts for the Ju52 norway addition..
I did notice that the sound file of the Norway Ju52 is pointing to a engine sound folder called,
Engine_sounds\GR_BMW 132_3X\Sound
whereas the engine sound folder in the ETO is called
DR_Engine_sounds\GR_BMW 132_3X\Sound
Note the DR_ at the start of the name. and this I think is were your problem lies.
I would copy the sound folder out of the w40_Ju52_BOF folder and paste it into the Ju52 Norway folder and overwrite the existing one.
delete the bdp file and give it a go.
The texture names starting with ETO, they are supposed to be like that, its the name the model files are calling for.
You also have the effects and shared files in your ETO install by defualt, so there should be no issue there. I'm sure it will be the sound file calling on a non-existant folder.
HTH's
regards Rob.
PS I did this here at work just comparing the actual files and what they called for, I havent verified the fix in game yet.