Sorry, I can't tell you anymore on the 190E. We have one, but haven't been into the cruise amp.
I could take you to the amp on the W123's with my eyes closed. I'm having fits with one right now, can't make up my mind if I should try the resolder trick (tried it once before and couldn't find any thing, so I resoldered everything possible..no luck) or just get a rebuilt one.
Once you open it up, the rebuilder won't accept it as a core.
Good hunting, would like to know where you find your amp. If your brother can do some good and needs another one to keep him busy, let me know.
Ernie