Early model Piper Aztecs only had one hydraulic pump as standard, the later F models all came with two pumps factory fitted.
When I did my Navajoo endorsement, the checkie doing it was also endorsing another company pilot Captain Ace Four Bars Baron expert.
Captain Ace Four Bars had a number of asymmetric go arounds because he would persist in leaving the gear up until late on the base leg, consequently final the gear would not be locked down and around we would go!