I can't tell from your pic but I did wonder if after moving house maybe the feed pipe has been swapped for the delivery pipe and your forcing water backwards through the ro? Long shot I know. Looks like a 200gpd unit you've got there so it must have 150 gpd membranes fitted if you say it's 300 gpd. Maybe the membranes aren't 150gpd?
I'm incline to agree. He has 2 membrane housings. I won't be surprised if the membranes were 150GPD and they have been replaced with lower capacity units.
The 150 GPD membranes just fit into the housing with out much of a gap. The 75 GPD membranes I had before they were upgraded where much smaller in diamt.
There is something about the way that the membrane housings are connected at the back that just doesn't look right. Unfortunately the photo isn't very clear.
Please can you take another couple of photos, one of the inlets and one of the outlets.
Also, I know that our water on Teesside isn't good, but that sediment filter is very red.