A couple of other things to check, especially with that age of trailer, make sure the wheel bearings are not loose, and make sure the tire inflation is correct, especially that the pressure is the same on both sides.
And Ray, IN...I appreciate the quote in your signature line. We really need a lot more of that mentality in our country these days. That could (and probably should) be a whole thread of its own.
2007 Country Coach Tribute; Cat C9 400; 2012 Ford Edge toad; Roadmaster Blackhawk 2 10,000 lb tow bar; Demco AF1 Braking System