1914, 1c Rose Carmine, Postage
Due (J1). Mint N.H. bottom plate no. 5541, imprint and star strip of
three, incredibly deep color, Jumbo margins, Extremely Fine Gem, Scott
Retail as hinged singles (Image)
1914, 10c Rose Carmine,
Postage Due (J3). Barely tropicalized original gum, rich color, wide
margins, Very Fine and choice, scarce with such wide margins, most examples
of this stamp are used or were cancelled before being sold, only a few
escaped as unused stamps (Image) 
1919, 4c on 4c Olive Brown,
Postage Due, "Zone" Omitted (J11a). Lightly hinged, deep rich color,
clear strike of the surchargeFINE. THE UNIQUE EXAMPLE OF THE 4-CENT ON 4-CENT POSTAGE DUE WITH "ZONE" OMITTED. ONE OF THE RAREST OF ALL CANAL ZONE STAMPS.
This error was likely caused when some foreign matter adhered between the stamp and the printing plate.
Ex Plass. Illustrated in Canal Zone Stamps on p. 239. With 1967 P.F. certificate. (Image)
1919, 4c on 4c Olive Brown,
Postage Due, "4" Omitted (J11b). Slightly tropicalized original gum,
fresh colorFINE AND RARE. IT IS BELIEVED THAT ONLY TWO COPIES OF THIS VARIETY EXIST.
Part of the "C" of "Canal" is also missing, which indicates that this error was caused by foreign matter blocking the overprint impression.
Ex Plass. Illustrated in Canal Zone Stamps on p. 239. With 1971 A.P.S. certificate. (Image)
1924, 1c-10c Postage Due
(J12-J14). Lightly hinged, rich colors, wide margins, Extremely Fine (Image)
1925, 10c Orange, Postage Due
(J17). Left plate no. 15510 block of six, slightly tropicalized
original gum, brilliant color, choice centering, Extremely Fine (Image) 
1925, 10c Orange, Postage Due,
"Postage Due" Double (J17a). Barely tropicalized original gum, vibrant
color, clear second overprint, Very Fine and choice, only 98 were printed,
with copy of 1978 A.P.S. certificate for block of four, this being the top
left stamp (Image) 
1925, 10c Orange, Postage Due,
"Postage Due" Double (J17a). Position 38, slightly tropicalized
original gum, bright color, Very Fine and choice, only 98 were printed (Image) 
1925, 10c Orange, Postage Due,
"E" of "Postage" Omitted (J17b). Right stamp in horizontal pair with
normal, Positions 82-83, brilliant color, barely tropicalized original gum,
Very Fine and choice, the error is only found on Positions 83 and 93 and
was caused by a foldover on some sheets, most stamps from this position
display more of the missing "E" than the example offered here (Image) 
1925, 10c Orange, Postage Due,
"Postage Due" Double, "Postag Due" Double (J17a, J17c). Horizontal
pair, Positions 83-84, slightly tropicalized original gum, intense
colorFINE AND RARE EXAMPLE OF THIS DOUBLE OVERPRINT VARIETY. ONLY TWO EXAMPLES ARE KNOWN OF THE MISSING "E" OF "POSTAGE".
According to Canal Zone Stamps, only one pane of 100 with the double overprint was issued. On this pane, two positions -- 83 and 93 -- have either all or most of the "E" of "Postage" omitted. The other example, from Position 93, has a straight-edge at bottom.
Ex Plass. Illustrated in Canal Zone Stamps on p. 240. With 1967 P.F. certificate. (Image)
1925, 1c Carmine Rose, Postage
Due, "Zone Zone" Ovpt. (J18a). Position 18 from the bottom right pane
in right margin part arrow block of twelve, natural s.e. at top, slightly
tropicalized original gum, few perf separations sensibly reinforced at top,
rich color, blue crayon "X" in sheet margin means pane was marked for
destruction, Very Fine and choice, rare, of the 75 which were issued only
approximately fifteen are known, the rest may be lost to philately, with
1969 A.P.S. certificate (Image)