if you have any questions on the other parts, drop me a line and I would be glad to look thru mine to see what parts are supposed to be there. I haven't touched mine in at least 25 years, but iirc, all the parts were there when I got it. Your's is a bit further along than mine, again iirc......
One of the reasons I skipped over this model and built the bulkheads flats was that the time and effort to make a decent looking center flow hopper would be huge compared to the commercially available and infinitely more detailed versions already available. There are times when $20-30 is easier to come by than 20-30 hours....
I instead built the bulkhead flats due to the lack of anything similar and otherwise available. And since it was my 1st Ambroid kit, they also appeared infinitely easier!