'86 420 Power Steering Filter: Where?

[Randy]

OK, I changed the pressure hose, opened the reservoir and found: no filter. There is a tan plastic device under a small nut on a threaded rod, with a spring under the plastic piece. In the very bottom of the reservoir is a flat steel plate with 8 holes in it, and it does not appear that it is supposed to lift out. I bought a Hengst filter, nr. E26H, and it will drop in the reservoir, but it's obvious it doesn't fit and it won't filter anything if it's in there. This car has the ZF pump with the blue tag. If you can advise, please do. I am changing the fluid, to Valvoline syn. The system has red stuff in it now.