Oh boy Mike, there's lots of discussion on FGRV about replacing axles and the reasons. In a nutshell, the rubber wears out, dries out, breaks, loses flexibility, etc. Your trailer is a bit of a lowrider, I noticed that the last time I saw it. New axle
will run you about $500, plus the cost of removing and rewelding. Utility trailer builders in your area should be able to order a new Dexter and do the work. I replaced the axle
on my Scamp
about 5-7 years ago. Good decision for me!
If you want to see how the axle
on your trailer is doing, put your fist on top of the tire and have Nancy go inside and jump up and down right over the axle. Careful, don't want to smash your hand, but you should have (always) one fist of clearance between the tire and top of the wheel well. If it doesn't move at all or very little, the rubber has lost flexibility. If you can't get your fist on top of the tire to start with, the axle is "dead." If everything works well, then you can have it taken off, spacers up on and bolt the axle back on to the spacer... that will make the replacement when it's time easy peasy.
Others have thoughts for Mike about the axle?