I would suggest starting with checking the pressure just to be sure this is a restriction in the orifice.
Here is a guide that will help with this:
Basically looking at the pressures will tell us what the issue is so I included a chart below that will tell us what the possible issue is.
I also put the system diagrams that will show locations of everything as you requested.
Please run through this and let us know what the pressures are and we can go from there. If you don't have a gauge set, you can rent them from most parts stores.
Images (Click to enlarge)
Friday, September 17th, 2021 AT 6:57 PM