I am not at all sure if one can tell much from bouncing up and down inside the trailer while it is stationary. Maybe others will know more. But I can say from past reading here that people tend to replace their Scamp
axles when the arm angle has changed so much that one can no longer insert a fist vertically between the tire top and the wheel well above it. As the axle rubber ages, the whole thing droops. When you run the risk of having the tire bounce up into the wheel well and wear the fiberglass there, something must be done.