I hate to disagree with the bearing buddy/grease zerk deal here, but maybe I can prevent some folks from frying brakes. Never use them. Pull everything, inspect, and repack. I've been through 3 sets of Dexter axles, different GVW's even, now in the past two years - only 2 out of the total of 12 brakes were not saturated with grease. Grease attracts dirt, so even the magnets were rubbing dirt into the magnet surface, as well ruining the magnets. I only knew the service history for sure on one of them - but the guy I brought the drums to for machining just grinned and said "EZ-lube axles generate a ton of business for me".
Were these over-lubed? Perhaps - but when the dexter axle manuals say keep pumping until you have clean grease come out - it sure implies that the seal back there is holding whatever you pump in. I used them once on Sundowner we had since new so I was sure of the history, and didn't keep pumping until grease came out - rather gave 2-3 pumps - and it wasted 3 of the 4 seals and wasted the brakes within 5K miles.
When you replace the seals, with the brakes/magnets, and all that nonsense - you will notice they are so similar to a normal seal for a spindle that you wonder what is so different about them that would allow them to handle hydraulic pressures exerted by a grease gun. The answer is they don't. And Dexter is really happy to sell you brake parts too - they are about 3x a normal set of shoes to get OEM replacement.
The other two trailers I asked the question of the owner first "Did you service this yearly and pump grease into those EZ-Lube zerks". They emphatically both said yes, sure that it was a good thing. I immediately factored the cost of a brake job into my offer - explained it to them, pulled a drum to prove it to one of the disagreeing owners. Bought them both and found 3/4 were totalled - one survived the grease gun.
Just an opinion - but I've had enough and won't ever use 'em. Hope this convinces a few others to pull the hubs and pack 'em the old fashioend way!
jon.