also on a side note.. if it wasn't the pinched tube.. it could have been that the filter on the wiper pump motor was clogged..
on my dad's '87 camry had the same problem on the front windshilds.. we stuck pins in the nozzles.. still nothing..
eventually i bought an aftermarket motor at kragen for about $20.. when i pulled out the old motor i saw the old motor's filter was clogged with BLUE stuff.. blue stuff from the windshiled fluid..i guess the coloring agent eventually gets clumped up together.. and bam.. clogged filter..
..now i cleaned it out and now use this
Prestone Bug wash
its about $1.00 more than the cheap 99cent blue cleaner a gallon but at least its smells real clean like and does a really nice job