MarkT is possibly correct--look in the oil tray.
Otherwise are you sure the spring ears have been forced straight to go across the stop bolt in the case & the mechanism tag when its at rest between gears.

I had to drain it out to redo the shifter shaft seal.
Without doing anything else, I drained the rottela 15/40 non syn and replaced it with the lightest dino oil i could find.
Walmart sold a gallon and a quart some off brand the rest was at least 3o feet 5 shelves high synthetic.
Anyhow, it still is rideable and ill have to get back in there maybe focus on that spring and recheck the shaft for trueness again.