The main live cable to the solenoid has to be removed and you should disconnect the battery first, however this means that the radio code will be lost. Therefore if you do not have the radio code you will have a problem, we carefully disconnect the solenoid live cable and shove it inside a rubber glove for insulation. The lower starter motor bolt is straightforward the upper bolt is a pain because it's hidden behind various heater/fuel/FBH pipework and cannot be reached with a ratchet etc we use a very short 13mm ring spanner. Once the bolts are removed the starter motor has to be carefully manouvered past the radiator and the oil cooler pipework.