The service manual does a good job of walking you through the steps.
What helped me was to have a number of paper cups that I labeled with the step number - as the screws or small parts came out during a step they went into the numbered cup. Much simpler to reassemble.
Many, myself included, had a problem with a color sensor during the recalibration steps after reassembly. I just ignored it and it works fine. I don't think it actually the sensor, just a flaw in the system and the calibaration probably wouldn't work even before changing the belt.
I did the recalibration for other replacements and indeed the same problem with the sensor.. I agree the sensor is OK but the calibration system has a problem somewhere... the sensor still works well...
( that is a good thing for the sensor is one of the most expensive parts)