WHAT EVER you do should you remove any or all of the wiper rods and windshield drivers please do yourself a big favor and soak & clean those puppies. lubricate them w/ a good dab of grease and lithium grease in the drivers after you remove all the old crud that was on them.
re-install and you'll be a happy camper when it rains.
the one trick i know for (a little) help w/ a vacuum type is to add say a coffee can size can, under the dash w/ two brass tubes soldered into the can. this acts as added vacuum