2000 Powertech diesel not cranking fast enough to start.

Wow Vulcan you read my mind. I am going to put new starter in tomorrow and see how it goes. I am going to jump it if it still is slow to check voltage that way. I am also going to try to turn it by hand to see about resistance. Batts. are a year old and I load tested them. Connections are all clean and tight. Can't get to ones on rear of cabinet. Need to use scope to at least view them see how they look.