Your half cylinder on top “Component #1” is not solid, so you’ll need to fix that first.
Your double disk “Component #2” is solid, though it also has too much geometry in there.
Ideally, you would model these again with less segments in your circles. You have about 1000 segments per circle. Try 60 or even 30 sides. This makes tiny faces which SketchUp refuses to draw. You can trick it into drawing them by scaling them up 1000 or 10000 times (because you have so many tiny segments), forming the faces then scaling them back down again.
Your half cylinder has 3 stray edges, 1 internal face and 2 reversed faces. These aren’t too hard to fix once you scale it up. I highly recommend Solid Inspector2 from the Extension Warehouse for finding these problems. Problems highlighted in red:
Your model is also quite far from the origin for all the size of it. Maybe this is part of a larger model?
Check the entity info to make sure you have 2 solids:
Then select the half cylinder, trim tool, click the discs and it will cut it away: