Exploding Body Parts

Hi guys and thanks in advanced for any help. I’ve got a puppet rigged with curve deformers for the feet and legs. The legs have a kinematic output which hook into the pegs for the feet. I’ll include a photo of the network view. I’m having a couple of problems. The first problem is that rotating the deformers on the feet causes the feet to change size. Problem two is that I needed to extend a scene. Using F5 to extend exposure though has blown the puppets legs up, not on every frame but every eight frames or so.

Again thank you for the advice.