We have an injector pump! (mostly) I'm just looking for a better (easier to move, smaller) syringe with a luer lock output. And I got the correct parts due to sheer dumb luck, and then found out what they are after the fact. LOL.
Turns out these do all the valving work we need. We don't need two valves and a T, the one part does everything.
Part No.: 79004
Qosina Medical HPLC Dual Check Valve, 3 PSI CP, Male Luer Lock with Swivel Nut Outlet Port, Female Luer Lock Inlet Port and Female Luer Lock Control Port
Cost should be less than a dollar each, but the trick is finding a source that will sell in low quantities. You can easily find a case of several hundred, but never 1. I got lucky with an eBay listing, which wasn't for this, but this is what was delivered. Can you believe it? The universe loves me. LOL.
The funniest part is that the add that I purchased from popped up while I was composing an email to a friend about how little luck I was having in finding the needed part... right there on the screen... as I was composing the email... (!!!) Can you believe that? So I ordered it, didn't get the part they advertised (which I thought I needed) but did send me /this/ part, which is exactly what I actually needed!
The injection tip is an 18 gauge 90' curved blunt tip for Luer lock syringes. Those are more commonly available. Again, I found these on eBay.
Now I just need to amend the code to run the servo, and mount it and the wire to connect it to the syringe.