What does "no contingent arrangements" mean in this context?

It means that if a part fails or malfunctions, you have no guarantee that the Company will swoop in and get you back up and running (no plan B is in place if a part fails), unless you have that in writing. If their machine shorts out your whole electrical system, for example, they don't promise to provide you with a generator. Likewise, if a part fails, they don't promise to provide you with a replacement machine while you fix your machine (or whatever it is that you're referring to).