As Alan Leslie mentioned the Johnson Viking 32, we have also replaced the original AMFA pump with a Johnson Viking. It is well-built, extremely easy to maintain, has a higher output than the original pump, and a handcrank in case the power or motor fails. I could not find anything wrong with with this pump with the Johnson Viking. I could not find anything wrong with this pump since we have had it installed. 
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Mark Mueller
Brass Ring  A54