Have you looked at the turbo yet? Looking inside the center section will often let you know how well the owner kept up on routine maintenance. Is it clean, or does it have a lot of black or gray gunk built up on everything? Also, if you can blow compressed air into the turbine and look at the compressor to see if wabbles, this will let you know if the shaft is bent. If it wabbles, it's bent and thats no good.

 

...it was junk bent shaft