Ultrafab tongue jack stops & starts in use

If yours is an authentic UltraFab (lots of fake lookalikes on Amazon) then it will have a 2 yr warranty. I've owned 2 and the only problem I've had was with the 3502 I had on our current trailer when the stop washer fell out. I emailed UltraFab asking if I could buy replacement parts but was told they had identified this as a potential issue because the stop washer in question had simply been pressed in place during manufacture. New versions now have this stop washer welded in place so I was offered an entire new jack, all covered under warranty, including shipping and any customs costs. My new 3502 has cables for both positive & negative and works just fine ... can't say I've ever had this issue you seem to be having but it might be worth a call or email to UltraFab to see what they have to say.