back for a 636... tips when buying?

hi folks
back in the market for a 636... looking to get either 05 06 models.... any tips on what to watch out for when buying one of these? common problems etc?
Thanks in advance.
back in the market for a 636... looking to get either 05 06 models.... any tips on what to watch out for when buying one of these? common problems etc?
Thanks in advance.