Though one can always attempt to rebuild a transmission without prior experience, it is always best to have basic mechanical automotive knowledge before attempting to do so, as the task is lengthy and labor intensive. With basic automotive knowledge, the transmission rebuild goes quicker and with less room for error.
A mechanic checks three different aspects before rebuilding a transmission system: transmission fluid level and condition, accuracy of the computer system, and thorough test driving and inspection of the vehicle to rule out any other possible cause of a transmission problem symptom. Transmission disassembly and rebuild commences once the mechanic identifies that the problem is indeed in the transmission system. During the rebuilding process, the mechanic inspects, cleans and repairs, or replaces the parts as necessary.