In order to establish the cause of dislocation you have to look further, as alophysio already pointed out, than the knee. This for the simple reason that a dislocation can be forced upon the patella by a impropriate movement pattern at the hip, Pelvis and the foot.
You should start with observing if there is any visible differences between the left and the right e.g. Valgus/ varus ankle, inward rotation at the hip.
Secondly are you sure it is the patella and not e.g. the fat pad between the Tibia and the Ligamentum tibiopatellare or a slight tear of the latter (this would change the direction of pull on the patella). You state that pain is felt in a rather obscure manner: felt on the lateral side of the knee while provocation is on the medial side. What sort of pain is felt? This description can help you to alocate what structure might be responsible. Any obvious referred pain?
What puzzles me is your 3/5 muscle strength, I assume of hip flexion and knee extension (SLR). Also your popping sound could come from e.g. Ilio Tibial Band (always on movement last part from flexion to extension)
A good examination of a knee problem can be found in the book; Clincal reasoning for manual therapists, I think it is chapter 14. Anyhow a book worthwhile getting.
Good luck.