You will have to search it your self from electronics book stores , internet , there is no direct book for repaires for medical instruments , if you know electronics and little technical for pneumatic/ hydraullic/ mechanical and rudimentry knowledge of medical instrument perticular you can start attempting for services , also you know what kind of instrument you have under taken like blood sampling , blood gas analyser, cardiac defribillators , X-ray machines , CT ,CET machine , sensors , display machines , spectrophotoscope and likes , does it need calibration , you have to refer service manual for that , working environment is also necessary that is different from general repaires . Also there are some diploma courses available specially for medicine related machinery , you get major information there