1997 case 580 super L hard start

I got my 97 super L 580 and she doesnt like starting.... Have to plug it in no matter what even if its plus 12 outside.... Kinda like some of the mid 90s 7.3L fords.. Usually if its plugged in it fires up after about 5hrs being plugged in otherwise itll just crank and smoke give it a sniff of starting fluild and away it goes. Changed lift pump filters batteries next is fuel lines and then im not sure what to try next maybe buy a newer machine

Any suggestions?
Thanks

1997 case 580 super L hard start