I have a set of Raleigh DL-1 handlebars in good shape, but with a problem-- one of the eyelets through which the brake lever travels is loose. The eyelets is free to wiggle in the hole in the bars. Is there a fix for this? Are they threaded? These bars are 1970s era DL-1 bars, standard shape and type.

Your LBS should be able to fix the brake lever issue. A DL-1 main problem is rod brake lever linkage parts are no longer readily available. A drum brakeset is safer and will last practically forever with no maintainance.

Well the LBS had never seen rod brakes before, so they weren't much help when it came to the loose eyelet.

Not interested in drums, I'm fine with the rod brakes. I've got a backup set of Eastman narrow bars on there for now, though it would be nice to find a full Raleigh wide set rod bar I guess.

I've wondered how those eyelets were attached. All of mine are tight (3 bikes), so I'm lothe to experiment in an attempt to help answer your question.

I suppose as a last resort, you might try epoxy?

Somewhat psychic-- since they aren't of much use to me in the state they're in, I tried JB Weld last weekend. The first attempt succeeded on the ferrule but not the eyelet. I re-clamped and tried again on the eyelet a second time. I'm going to let it sit awhile in the clamp until I know it's cured fully. I did the usual "overnight let sit". I wonder if a little more time might help it out somewhat.

They were probably press-fit in.

I'd pull it out, clean off the epoxy, prep the mating surfaces and silver-solder it back in. Even regular solder and a propane torch will work.

That sounds like the next stop if the epoxy doesn't work. I give the epoxy 50-50 chances at best. I really like JB Weld on metal-to-metal applications because I've had luck with it in the past. But this one is trickier.

I agree, I like JB also.
Maybe spray some carb cleaner, or electric spray around the joint, to clean out grease or oil, before working the epoxy in.

I'd think you'd do a lot of damage to the chrome finish if you tried resoldering with a torch? I still think epoxy is the way to go (psychic bike guy says...), but agree that proper surface degreasing is essential.

Quite likely it would, it's just plating so it's not the most durable. I'm not sure at what exact temperature it suffers damage though.