stripped splines on wiper arm

[BEJinFbk]

I've fixed a few just by using a sharp pointy object and scraping
all the soft metal out of the shaft splines. That often provides enough
bite to hold the arm. Just don't tighten the nut too much!

I also read about a guy wrapping small guage solder around
the shaft after cleaning out the splines, with good results.
Again, go easy on the shaft nut...

Best of Luck!