[1] Top cupping or bowing [2] Inbalance of moisture content between top and bottom surfaces, Oiling only one surface [3] Apply oil liberally to concave side. If not corrected within 2 weeks, tape plastic (ie. plastic liners, dry cleaning wrap, etc.) to the convex side and oil the reverse side every day. Top will adjust to new humidity and correct itself. [0] 
Warpage
P r o b l e m
E n d C h e c k s
S p l i t s
W i n d S h a k e s
W a r p a g e
R a i l E x p a n s i o n
S t a i n s
D a m a g e
M i n e r a l S t r e a k s