Just to add to this ***warning M.O.K.O's head spoilers*** you have to beat Magnolia and go back to the starting room and shoot at the middle of the ceiling (the middle of the pit you fell from) then once you "kill it" the head will drop and so will a flare gun - ( a nod to the buddy using it to get help but also an explosive weapon to get the leg in the second floor) these wont drop until after you beat Magnolia but if you use an explosive weapon to boost your self into the ceiling you can take damage. (for whatever that's worth)
lil more info if your thinking about using the random guns every room curse from the devil girl (every room you get 2 random weapons and that includes the robot parts) they don't work when you try it just says " you try to jam the part on but you realize its just paper Mache" so don't waste your time.
both of the parts can be found on your own by reading the M.O.K.O logs 1 and 2 the hint is after the MISFIRE: part.