I double checked the Europa service manual and the Renault 16 manual. Both have hardly anything for overhaul specs on the Solex carb. The 16 also came with a Weber DIR carb. That they list full specs for.
Back in the day, the Feds required carbs to be “tamper-proof”. Manufacturers then made emission carbs that were not meant to be serviced. Minimal parts and few specs were available and whole carbs being the preferred option. All ok-ish when they were new but a disaster after that.
Myself, I would switch to a Weber carb. It was a very common mod back in the day. YMMV.
One other issue is with the stock air cleaner. On a Renault, the inlet “snout” faces along the engine and is supported at its end. There wasn’t room on the Europa so Lotus turned it sideways and left it unsupported. This sets up a vibration that works the carb top loose. I would safety wire the carb top screws to prevent this problem. Don’t use thread locking compound. That way lies disaster with stripped screw heads and worse.