Winnebago High beam replacement

Just like a double pane window, if the seal fails eventually you will end up with moisture in and 6 or 7 years is about average before failure. During the day the air inside heats up, expands and leaks out. During the night the air inside cools, condenses and pulls in moist night air. Any metal inside will eventually rust and replacement is the best fix but it will happen again some day.
Sealed, glass beams back in the 60's and 70's seldom had the problem but the foreign manufactures don't properly seal the plastic.

Two travelers,

The water is getting in from elsewhere. :) Perhaps a failed seal on the lens?

Are the front lenses plastic like most are now? If so, the brute force way of dealing with the issue is to put the vehicle on level ground, use an 1/8" drill right in the center of where the water is collecting and drill through it from the outside. That should allow any water to drain out.

Good Luck,

~Rick