88 Camry 4-cyl. SW: is P/S pump shot?

I replaced the steering rack with a new one around 3 months ago. topped of P/S reservoir. Turned the steering through several times and topped off again. Worked for maybe a month, then when my wife was driving it, she said the P/S was making loud noises and seemed to have lost the power steering. I found the reservoir empty. No wonder. So I refilled it and checked for leaks....did not find one. WHere did the fluid all go? Well after refilling reservoir, there are no longer any noises, but the P/S just doesn't work, have to muscle it into turns. I can't see why loss of flud would have damaged the rack, so I guess the P/S pump is shot? Right? But when I remove the reservoir cap and watch the fluid, it seems that there is still a flow or movement there. Unfortunately there seem to be no connections so that I could put a press. gauge on the lines and check if the pump is no longer working. Guess that I just have to replace the pump and figure out what happened to the fluid ?