So I've been having this issue recently where the wiper arm will loosen the 13mm nut enough to break free. I had replaced a burnt out motor the past weekend with a brand new one, tightened everything up and it all worked great for about 30 seconds then the blade stops and i hear the motor spinning. I check and the nut is fully loosened and sitting at the tip of the bolt. I tighten it down again, same thing happens. I decide to go straight for the Loctite blue and it works... Almost for a whole 30 minutes! The arm does have a ring engraved where the teeth of the nut dig into it so I know it's not helping to have a locking nut on there. The Loctite should have done the trick unfortunately it still broke loose. Does anyone have any other suggestions? Should I replace the arm the motor shaft runs through? Use Loctite red? What is causing so much vibration just from daily usage that would cause a tightened lock nut with loctite to break free?