A trip down the rabbit hole of YouTube lead me to this gem. This was filmed around the time of my earlier visits to Switerland, before I started taking a serious interest in modelling the Lötchberg line and didn’t take detailed notes of the train formations. On later trips just after the turn of the century things were less varied, with EWiv push-pull sets on all but a handful of international through services. But back in 1990 it was a real mix; just look the very first train, with it’s mix of Swiss, Italian and Belgian coaching stock, and a rare BLS livery EWi restaurant car.
It’s notable just how few trains are uniform rakes; proof that you don’t need a full rake of anything to make up a realistic train. In particular the EWiv coaches were still being delivered, and the BLS didn’t have enough of them to make up complete rakes, hence the sets make up from a mix of EWiv and older EWi and EWii stock.
The other thing of note is the Re4/4Iv locomotives, which were operating over the Lötchberg at the time. Only four were ever built, and the class never went into series production. All four were eventually sold to the Südostbahn.