Just a quick question, Deformation of parts would mean compressed spring power is legal no?
As long as the spring is part of your robot, and you are storing energy by deforming it from its neutral state, then yes.
A compressed or extended or torqued spring or other elastic material is exactly what we understand this rule to mean.
More years than not, we come up with at least one robot concept that involves a big windup torsion spring. Last year, I wish we’d thought of tethered stackers in time to make one powered by a spring.