Had similar problems with a 4 bay site built in the 70's. Not enough pressure for hydrominders to work properly, RO would throw low water faults. etc. Installed grundfos Scala 2 booster pump... keeps everything at 80psi. Works perfectly...except they are a little pricey and the build quality is...
Had this same problem a couple weeks ago. Try looking in the wire/junction box on the motor. Ours was full of water. The condensate drain had plugged up. I redid the wires with wire nuts. Knock on wood, so far so good. This was an 18 month old laser 360 plus