ncrease in the risk undertaken by the guarantor, the obligation of the [".15] guarantor is not discharged."' Roels, 240 III. App. 3d at 582, quoting Essex International, Inc. v. Clamage, 440 F.2d 547, 550 (7th Cir. 1971). [HN4] "Whether a guarantor is exposed to an increase in the risk it originally undertook is a