If you have used plain water in the reservoir then you can exp it had it had water in the reservoir you can expect slime to have built up and clogged the nipples and or hose.
I got my car from Florida and it had water in the reservoir and it had clogged the nipples, hose and the outlet from the reservoir. I had to take the reservoir out as it was filled with water and slime.
If you take it out consider replacing the reservoir as they tend to get brittle and crack. Also clean out the tank area as the passenger side of the cowl drains into this area and dumps dirt and debris in this is area. There is a PDF ‘HowTo Replace the Reservoir’ and you should read this as it explains how to open, clean and adjust the jet from it.
Look at the nipple first and if it is clogged with slime you know you have to clean the system, unplug the lines to the nipples and see if they are dirty, listen for the pump motor all the time.