1907, 1c Green & Black,
Horizontal Pair, mperforate Between (22a). Lightly hinged, deep rich
colors, wide margins, Extremely Fine, it is believed only 50 were printed
(Image) 
1907, 1c Green & Black,
Imperforate Horizontally (22c). Vertical strip of three with horizontal
perforations at bottom only, slightly disturbed original gum, deep rich
colors, wide margins, rounded corner at bottom left not affecting error
pairVERY FINE AND CHOICE. A RARE EXAMPLE OF THIS IMPERFORATE HORIZONTALLY ERROR. ONLY 20 PAIRS WERE ISSUED, AND MOST HAVE BEEN LOST TO PHILATELY.
According to Canal Zone Stamps, the top five rows of one pane had the horizontal perforations omitted. Most were probably used, as only three unused pairs and two strips of three (both with perforations at bottom) are known.
With 1969 A.P.S. certificate. (Image)
1907, 1c Green & Black,
Imperforate Horizontally (22c var). Bottom margin single, slightly
tropicalized original gum, Very Fine and choice, scarce variety, there are
only three unused vertical pairs and two unused vertical strips of three
(with horizontal perfs at bottom) recorded of the Scott-listed No. 22c,
Scott Retail for the listed variety is $2,250.00
(Image) 
1907, 1c Green & Black, Double
Ovpt. (22e). Sheet margin at top, lightly hinged, proof-like
impressions, Very Fine and choice, only 300 were printed, with copy of 1978
A.P.S. certificate for block of four, this being the top right stamp (Image) 
1907, 1c Green & Black, Double
Ovpt., One Inverted (22f). Tropicalized original gum, beautiful colors,
wide margins, Very Fine and choice, it is not known how many were printed,
approximately 20 are known, blue Colman backstamp
(Image) 
1907, 1c Green & Black,
Inverted Center, Ovpt. Reading Up (22g). Sheet margin at top, slightly
tropicalized original gum, perfectly centered, deep rich
colorsEXTREMELY FINE. A SUPERB EXAMPLE OF THE 1907 ONE-CENT BALBOA WITH INVERTED CENTER AND OVERPRINT READING UP. ONLY 22 COPIES ARE KNOWN UNUSED.
According to Canal Zone Stamps, one pane of 100 was printed. It was sold in March 1909 to the Panama Railroad Co. and all but 22 copies were used before the error was discovered. Only about thirteen used copies were recovered after the error was noticed. The stamp offered here, with sheet margin at top, is especially desirable.
With 1971 A.P.S. certificate. (Image)
1907, 1c Green & Black,
Inverted Center, Ovpt. Reading Up (22g). Light strike of town
datestamp, almost perfectly centered, rich colorsEXTREMELY FINE. A RARE USED EXAMPLE OF THE 1907 INVERTED BALBOA ERROR. ONLY THIRTEEN USED COPIES ARE RECORDED.
The previous description describes the discovery of this error. It is scarcer in used condition.
With 1978 P.F. certificate. (Image)