Forgot to say, another excellent degreaser and all around cleaner is good old Proctor and Gamble's Mr. Clean. Like the old jingle says, "Mr. Clean gets rid of dirt and grime and grease in just a minute, Mr. Clean will clean your whole house, and anything thats in it!"
I once restored (just by cleaning it up) and old Kirby 500 series that i found in the trash after an estate sale,,no one wanted it so whoever just set it out at the curb with the trash,,there was absolutely nothing wrong with the machine at all, except it had been sitting in someone's attack or basement for years, and was covered in dirt and grime, and i mean COVERED,,was at least 2 inches THICK.
I mixed up a solution of water and Mr Clean in a spray bottle, got some old towels and went to work. I sent the carpet nozzle and brush thru the dishwasher, and the bag thru the washing machine on slow with cold water,and Mr Clean.
Sprayed down all the surfaces with the Mr Clean solution, wiped it all off,,and it was beautiful. Of course the metal needed polishing, but at least i got rid of every speck of grime, grease and dirt. The whole machine even smelled clean afterwards. Sure enough, Mr. Clean cleans anything.