[fintstone]

Loosen the clamp and take the pump out to work on it. Those fittings should not be too tight, so once you had better access, you could probably use an open-ended wrench at an angle. Certainly, something with long jaws like an adjustable wrench.

If that does not work, you could probably put a couple of fairly large nuts (one on either side, opposite the blue terminals) so that they extend beyond the terminals. Then use some large vice grips or a large adjustable wrench to lock down on the nuts to hold it while you loosened the fitting.