The nozzles on our 560 were caked when we got it also. I used a high E string from a set of light acoustic guitar strings to clean the jets. That let me get an inch or so down the nozzle and wiggle a bit. Good job of cleaning, but not for aiming. I'm going to use Mike's straight pin tonight to do the aiming!
I've used old guitar strings for a number of other cleaning and wrapping jobs, they have high tensile strength and small diameter. Most larger music shops have single strings available for cheap, the B and high E are all you need.
'02 C230 Kompressor
'89 560 SEL "Frau BlueCar" (retired April 2004)