Ok recieved used blower today and guess what it WORKS, only problem is it is very loud, not sure he has sent me a duff unit or I haver installed it wrong, am I right that there is only 3 screws connecting the blower to that black thing, also my old blower had a plastic screw on the top of the fan not sure what that was for this one doesnt, please tell me I have installed this thing wrong as I finally have heat but it is way to loud on anything bar 1.