Chewing gum, the scourge of cleaners everywhere, is one of the more challenging substances to remove from carpets, upholstery and fabrics.
The reason gum sticks so well is the polymers, plasticizers, and resins that make gum both chewy and durable. These materials do not release from fabrics very easily—and old hardened gum can be the worst.
Chemspec Liqua-Gel (or Prochem Citrus Gel, as an alternative) works great on gum. Rather than drying to dissolve the gum layer by layer, it uses a formulation with "tines" somewhat like a fork to poke holes in the hardened skin of the gum. Apply Liqua-Gel and allow plenty of dwell time and you’ll dissolve the gum from the inside out.