Hi Claude,
Our assessment starts with some simple frame checks that could help avoid wasting time on a troubled bike:
.. are the forks bent or misaligned with each other?
.. any paint ripples / cracks especially around the head tube and top of downtube?
.. does the headset bind or stick when the bars are rotated back and forth?
.. is the quill stem frozen / rusted to the steerer tube?
.. is the seat post frozen in the seat tube?
If the answer to any of these is 'yes' you may be looking at an extended repair or having to trash the frame. Two minutes and two tools can save time wasted by trying to anything else first.
We also consider the quality level. If the answer to these questions is 'yes', and the bike is not in pristine condition, it would not be accepted:
Does it have steel wheels?
Does it have stamped steel brake arms?
Does it have a one piece, or a cottered, crank set?
My 2 cents.
Dan Craven