I assume that you are talking about the AView spring-damper element. This is a composite element, a so called user-defined-entity UDE that is composed of a number of basic building blocks. A SForce supplies the force description for the solver, a spring_damper_graphic provides the graphic apperance and variables are used for a number of things. All of these are children of the spring-damper and besides being modifiable through the spring-damper dbox they can also be modified individually, but sometimes with unpredictable results.
Right click ont eh spring: "SPRING:Spring_1", then choose "info" in the pop-up menu. In the info window, click "Children". Now you see everything that belongs to teh spring damper element.
Now click on ".model_1.spring_1.spring_graphic". Then click "Modify". Now you get the dbox where you can change the geometry (I suppose that it is really the geometry and not the icon that you're after). The diameter is by default set to a parametrized expression that is 20% of the length of the spring.
