If your dolphin striker is not securely attached to the mast step/front crossbar, you risk breaking the crossbar. I seriously doubt hose clamps and epoxy are going to do the trick. The striker and crossbar need to be one solid unit to be structurally sound. If the post is moving up and down, it means the whole crossbar is able to flex. It should be fixed correctly, not jury rigged just to get on the water.

sm