A 24V motor suitable for the D60 watermaker is available from industrial sources in the USA for ~US$300. Parts for the CAT high pressure pump are also available from CAT. Dessalator's spare parts prices make Volvo's look a bargain, and that takes some doing!!!!
I assume that your D60 does not have an additional low pressure feed pump, which most of the larger later model Dessalitors do. Be sure that the pressure valve on the watermaker control panel is fully open. If that is closed, priming can be difficult or impossible. I also assume that the pump was not run dry at any time except during your priming attempts.
If the pump is turning, the fault is most likely in the water feed, because it is unlikely (but possible!) that the pump could fail totally over the maintenance period. The water feed is probably restricted. If you haven't done so, try changing the feed water filter, see if that helps.
The pump inlet is below the waterline, so if you disconnect the inlet from the pump copious amounts of water should flow out when the seacock is open. If not, track down the debris clogging the hoses or other issue with water feed.
If the inlet water is free flowing, and the pump is running, and nothing seems to be coming out, try disconnecting the outlet hose from the pump. If the outlet doesn't push lots of water under high pressure, it is possible the pump needs a rebuild. If the pump is not leaking water, the internal check valves could be bad, but it seems odd that all of the cylinders would go bad at once.
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