I can think of 4 things to try, Fred. Simple Green works great. Ammonia in water and vinegar in water both cut grease pretty well but ammonia is better if nastier to work with. If all else fails, Tri-Sodium Phosphate will work. The secret to all of these is to work on small sections and get the water off as quickly as possible. Use one sponge to put the cleaner on, rinse with another one in clear water, and dry with paper towels. Wear gloves and eye protection. Follow label directions.