Marty,
I am sure you have thought about the step binding.  My old '99 had a few problems and was binding and I found out that there was some corrosion in each of the moving areas.  That was enough to pop the automatic reset breaker.  After breaking the step loose with a crowbar and hammer, I used some rust inhibitor then oil and did not have another problem with it for the next 3 years.
Roy Warren