If you git 20 years out of the rubber inside a torsion type axle of any make or model you have done great! Like any other spring a rubber/torsion axle will also settle over time resulting in less suspension travel, lower ground/rear overhang clearance and a MUCH rougher ride.
All the Amerigo's I have owned sat very low if they still had the original worn out torsion type axle under the trailer. The big result is that you will have tail dragging issues when going up a sloped driveway or road transition and ROUGH RIDE for the trailer.
The solution to these PROBLEMS is to install a complete new axle with new electric brakes
and a higher working down angle on the axle than original to lift the trailer body higher off the ground. Yes I recommend a higher down angle on the new axle than the originally specified by Amerigo when they built the trailer. The trailer will pull so much better with a new axle at a higher down angle giving you much more ground clearance and much more rear overhang clearance.
A lot of value, benefit and trailer improvement for the low price of a new axle (about $350.00) + the cost of installation!
This is the first modification I would recommend be done to Amerigo trailer as I can guaranty you the original torsion type axle is worn out!