And as far as rusted washers go, remove the ones that have rusted and take one to ACE hardware on Milk street in Westborough or to Koopman's Lumber on Worcester Street in Grafton and get a matching one in stainless steel so it'll never rust again. You could try Lowe's in Westborough on RT 9 but I've had spotty luck with them lately on hardware.
Sorry, but I don't know what you've got to start with so I don't know if what you need is English or Metric but either of those places should be able to fix you up for under a dollar.
I also don't know what Henry uses for wiper arms. Marty's picture looks like a later VW arm (post '72, when VW went to an "American-style" arm) but I can't be sure without having one in hand. You could take off the remaining one (or the one which came off, if you still have it) and go visit Angel or Kevin at Autopart International on McKeon St. in Worcester (off of Cambridge ST. near Holy Cross Univ.) to see if they could match it up.
As far as the AC knobs, that set screw is key and pretty obvious, if that's what the problem is. I would check down in the carpet to see if the set screws have fallen out and are hiding in the carpet. If they're among the missing (maybe gobbled up by the Vacuum monster?) then those, too, can be had at ACE hardware. Don't forget the Locktite when you put them back in.
