Make sure the jack is grounded good to the frame. That is accomplished by the jack being mounted to the frame with three mounting bolts. After my new jack was installed it did not have a good bond metal to metal from the jack to the frame and sometimes it worked and sometimes not. My first clue was seeing sparks at the frame and mounting bolts and the bottom off the jack was hot. Removing the mounting bolts and scuffing up the mounting flange and frame to get a good (ground) bond did the trick.
2008 Modified Surveyor 303
2010 Dodge Ram Laramie 4x4
2013 From FL to Pick up Surveyor Islip,LI, PA,NY,VT,NH,MA,CT,NY and Home
2014 Sebastian Charleston,SC to Finger Lakes, Lake Erie, Lake Cowanesque,PA and home
2015 Sebastian to PA,NY,WI,MN,return to NY and home
2016 GA,SC,NC,TN,KY,OH,PA,NY,to Sebastian,FL