The filter is in the resevoir, just hidden from view. If you open the resevoir top and look in, at what looks like the botten of the resevoir, there are a series of holes - that is the steady plate. Drian off the excess fluid by the previously mentioned techniques, then lift the steady plate. Underneath the plate you will find the filter, and the true bottom of the resevoir.
Replace the filter and steady plate, then fill with fresh fluid. Start the engine, work the wheel stop to stop and top off the system.
Many reccommend ATF, but I prefer power steering fluid. Some AFT additives are not good for the steering system and can result in damage, plus the difference in color, smell and taste (hmmmmm, hmmm)help pin point where the spots on the garage floor came from.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.