I have no idea what a "banking" noise is. The Deere 8 piston pumps though, tend to hammer a lot when the stroke-control valve an seat gets worn. It happens more in the bigger USA pumps, 2.4 and 3 cubin inches. But to a lesser degree, also happens in the little German pump you've got.I have 1630 -79 with an eigthport hydraulic pump.
At idle RPMs are there a distinct banking noise from the hydrulic pump
What are the most likely valves to make this noise?
When that vavle gets worn, the pump make a metalling rattling or hammering noise until you put a demand on it (like jiggling the steering wheel), or rev the engine up.
I thing there are a few things missing in that diagram you posted. The stroke-control valve and seat will be underneath and directly in-line with the big adjuster bolt and jam-nut. I don't see the adjuster in your diagram.
The stroke control valve and seat are numbers 14 and 15 in the diagram I attached.
You don't need to take the pump out to replace that valve. If you want to pull the pump anyway, a seal kit and maybe new piston springs is probably all you'll need.