new holland boomer 54d

I'm having problems finding a soft plug to install the engine block heater in a New Holland Boomer 54D tractor.

Was running the loader on my 160 hour boomer yesterday and it went into limp mode..."Stop" light came on, and error code 3410 came up. I looked things over and found that the trans fluid was low, so I topped it off. Started it up and the code and limp mode came back after a minute of running...

I have an intermittent problem where error code 3350 appears as the instrument cluster is trying to excite the alternator over the period of half a minute or longer. The service manual describes the fault related to the error code as "terminal 50 (crank input) always on", and "engine cranked for...