Whats happened to your furby is the tilt sensor has deteriorated with age and the little ball bearing inside the sensor is stuck. The solution is to take your furby apart to clean the sensor and reset the bearing. look online for more comprehensive guides on taking ur furby apart safely. The tumblr furby community has a lot of resources for repairing 98 furbys and this is how i fixed mine with the same problem as yours. Once you have the electronics exposed, on the front left hand side near the base is a white cylinder (sometimes but uncommonly red), this is the tilt sensor and will have the bearing inside it. You will need to very delicately open the cylinder, remove the top brass ring and ball, clean those, but do not touch the bottom ring since its attached to the board. Once its cleaned, put it all back together and he will work.