The perfect solvent, ideally, is carbon-tetra-chloride affectionately called carbon-tet. It was the mainstay in the past as it was "dry-cleaning fluid". Unfortunately chronic exposure in this industry increased the risk of liver cancer, so it got banned. It is also very good for cleaning oil off rubber parts, tape deck pinch rollers etc. It has the effect of "reconditioning rubber surfaces". It got replaced with trichloroethelene, for a while, but that has its own toxicity too. I remember they day I used the last of my bottle of carbon-tet, nothing was ever as good.
The common modern de-greaser solvents now are marketed as "contact or circuit board and switch cleaners". They have negligible residue and don't provide any lubrication either, so after cleaning potentiometers for example, some lubricant needs to be added. A typical product from CRC is:
http://www.radioparts.com.au/product...c#.WODNIvl96t8
(notice on the list of ingredients all the things it doesn't contain)
You can use this to de-grease the chassis, along with a brush is a good idea. It won't dissolve electronic parts or paint or attack plastics/insulation or circuit board coatings.
(There was a great episode of Lost in Space, in the mid 1960's, based around a bottle of carbon-tet. Dr.Smith, had left the lid off the bottle of Carbon-tet or used it up. With the help of an Alien teleporter machine, the young Will Robinson was able to travel to Earth and bring a bottle of carbon-tet back with him, the story is here:
http://lostinspace.wikia.com/wiki/Re...om_Outer_Space )