Well , thanks for the thanks , I see you've found and checked the fuse , next is to check the ground wire , then power at the switch , into and out of ; when you've done those tests , internal issues with the jack motor is the most likely issue.
I do hope your testing with a multimeter or a 12 volt test light , because when it comes to fuses " Looks good, isn't good enough ! " it has to test good.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.