I had trouble with mine on refitting to the second vehicle I had it on, because it wouldn't bleed until I held the reservoir way up high to get the oil to drain down, once the oil was into the pump it was fine. So fine, in fact, that the returning flow sprayed out the top of the reservoir (which I left off) all over the bonnet padding, engine, garage roof, me, tools .....
Needless to say I left the lid on the reservoir when I fitted it to the 110