Good post, but I would pick you up on terminology! Thorough Examination is the correct term, whether it be under PUWER or LOLER.The person undertaking the inspection (and i deliberatly use the work inspection, it is not a test at all) must be independant fromt he person who undertakes the repairs (you cannot mark your own homework)
The person undertaking the inspection must be competent. Do be competent, you must have both practical and theoretical understanding of the topic.
The easiest way to achieve these requirements is to attend a specialist training course. However, if you feel you can demonstrate the requirements, then do your own, as long as you dont fix the machine as well.