[Monkey Wrench]

pul off your wiper arms, turn them a notch and reinstall.. If you want to look at the thing that makes them park int he right position its part of the wiper motor gearbox, open it up..
you can lube it and how it works is pretty self explanitory.. if you find bushings on the wiper arms maybe give them some lube.

If you take the motor apart check the magnets, they are bonded to the motor case, I've found them in a state where the motor ran but the magnets had come loose and were stuck to the armature, miraculously it ran slowly but there should be an air gap. the magnets dint go anywhere , they couldn't turn with the armature but the armature was all polished from them being stuck to it.. I cleaned and glued them back with JB weld and that fixed it..

i've had issues with the serrations wearing out then the wiper arm won't lock down properly and stay where it should, then the woper arms get out of position.. . I stuck it back with some JB weld, now a few years later, I'm trying to figure out how to get them off because I want to check the seal for my heater motor so I want to remove the grill which means removing them, and realized JB weld is good up to 600 dregrees so I' m not sure if I can unstick them by heating.. better to replace but I needed it for work,, maybe locktite is easier to break with heat. you can look if its been slipping about and if so, well that's another issue you may see..

I think what can happen is the wipers freeze in place then when switched on there is quite a bit of torque there and the blades can' t move , then the wiper arms can strip, especially if they are a bit loose to begin with.

i read the symptom again, if they go down before going up Id have a look at the gearbox near the motor. there is a micro switch there maybe its loose or similar. sometimes the whole mechanism can develop some slop too.

you can check with others to see if its hard to remove all that as an assembly , it muight be a but buried int he dash but otherwise its usually mainly just the wiper arms and maybe a couple bolts.. maybe its possible to change bushings and such to remove the slop if that is an issue.. I think there may be some bronze bushings in there that dry up and never get any more lube due to the location, on some cars you can access them from under the dash and pull out the whole contraption. The bushings may not be hard to replace if their holes go all egg shaped.