Have a chance to pick up a Kawasaki 2000 900 STX for nothing. With good battery, starter engages but engine jerks and won't turn over. Thinking motor might be seized, but since motor seems to be jerking maybe pump is seized (former owner thinks this might have been issue before--he's kind of clueless). Any hints on freeing this sucker up? Then I can figure out if there are other problems . . .