Presstek 34DI - noise from impression cylinder

I tried printing today after the imaging process but I realized only two colors are printing on the sheets(yellow & magenta) which is tower-1, cyan and black is not printing on the sheet but i can see cyan and black ink on the plate and blanket. However, a noise was coming from the impression cylinder area. Please, kindly help with solution. Thanks

 

Test the cylinder solenoids (magnets) from tower cyan +black, if is going ON.!

look for loose wires, or air leaking, etc...

 

Thanks for your response CHOKE. However, is it possible to guide me on how to test cylinder solenoid on the tower.

 

Please use the schematics electrical and Pneumatic.