#9 is called a purge solenoid valve. Black plastic thingy with an electrical connector on it that's not shown in the schematic, but is shown with the individual part photo. List price over $100 -unreal.

Here's a link to all the individual parts
https://parts.volvocars.ca/a/Volvo_1998_S90-4DRS-WO-SR-30l-6-cylinder-Fuel-Injected/__5699823/Carbon-filter-with-fittings/GR-68920.html

What I've done with similar vacuum system rubber elbows where the ends split with age is wrap them tight in electrical tape and use tiny zip ties to keep the tape from unravelling. Proper black UV zip ties last longer in an engine compartment than cheap white ones from dollar stores. If it's one or two with a split at the bend then I might try using black RTV on them and let it dry before taping -just don't let any get inside the hoses, but at that stage it's maybe time for new elbows. Called a rubber coupling p/n 3531116, available from Volvo for a few bucks each. Any suitable diameter will do from a general autoparts store.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now