Holding tank purge pump

[Polyman]

Hello:

I am in the process of fixing the holding tank of a Passport 40 yacht and found out
that it came with a pump that was meant to be able to purge the tank when not at
a marina. The previous owner told me that it never worked, and between his
ownership and mine makes 17 years. The attached picture shows the device once
I power washed it. The motor is inside the rubber bag in the middle while the bottom
seems to be an impeller. The waste is pumped out through the hose partly visible
in the top side of the assembly.

I was trying to fix it, but even assuming I can disassemble the severely rusted,
galled and corroded frame, I am wondering how easy it would be to locate compatible
replacements for motor and impeller.

Would anyone be able to suggest a replacement for the entire assembly? Even if
the dimensions are not perfect, I can, within reason, create shims and adapters.

Thanks
Tony