Good advice that. When my original pump died I couldn't afford a genuine one so I went the cheaper option. It worked but it was noisy as hell and i wasn't sure how long it would last. It was a bugger of a job swapping it over and it's one of those jobs I only want do once.
So I cut a square hole over the pump area in the floor but then I found that a cross member went right over the pump so I still couldn't get it out! Then I cut the cross member out of the way, all this very carefully I might add. I then made up two small top hat sections and fitted them around the edge of my cutout to give it some form of strength. I found a bit of s/s for an access cover and screwed that down with small button head self tappers.
So next time It will be a ten or so minute job not two hours.