Mine does the same thing and i have a feeling it has to do with the water getting in there because of that weather stripping they put in there that has a gap and allows water to flow through. Mine was fine and then only starting acting up after a couple of years, i assumed because some water got in the components and got it all wacked out...
The other annoying part is that you can't simply replace the wiper (that ive found) and the dealer has to do it. With all of the extra wipes when the glass is dry, it tore the wiper and leaves an arch in the middle of the wipe area of unwipped water....
2009 KK Sport 4X4
235/75/16 GY Wrangler Silent Armor
Custom Crossrails,Thule Ski/Snowboard Rack,
Silverstar Ultra H-13, Cobra 75 CB Radio W/ 2' Firestik
Relm 8125 Fire/EMS UHF/VHF Radio
1989 YJ 2.5L Stock (for now)