I use 90% rubbing alcohol for machine guts. My experience has been that it's the fastest thing to clean and unfreeze parts that are supposed to move but don't. Dab a Qtip soaked in alcohol where you want to loosen and dissolve old gunk/dried oil, and as soon as the part starts loosening up then oil it to flush out what the alcohol dissolves. Saves a lot of time versus penetrating oils and heat. Just be very, very careful when using it, especially on a black machine as it will dissolve the finish/ruin decals if you drip it on the outside.
Cari