Well I may be "THE @mobile-joat" but to properly access the situation from a few pictures can be difficult... Here's a suggestion that may do the trick... Sometimes fittings are not molded or formed close enough to have a tight fit. So to compensate for these issues I'll sometimes use (2) washer/gaskets in the end of the line. However, either way you're going to have to use a pair of channel locks or pliers to get it tight. Also consider when you are finished working on it you may have water leaking around the pump inside the machine I've seen it happen many times thinking it was a line and ended up being a bit more of a problem than expected. Hope this helps.

The @mobile-joat