US 633, 1.5 Cent Harding, Perf 11 At Right Error?

While sorting Bureau precancels I came across the following stamp. It appears to be a Scott 633, perf 11x10.5. The left side is perf 10.5, but the right side perforations are 11. (Top and bottom are perf 11 as expected.)

Is it possible this is a perforating wheel replacement similar to the "perf 10 on one side" varieties of the perf 11 stamps in the earlier printings of the 4th Bureau issue? I do not see any such 10.5/11 error varieties listed among the compound listings

It bothers me a bit that the left and right perfs don't match, but it is no different--I suppose--than this stamp found on the swedishtiger site:



I don't know how the perfs measure on the above stamp, but they certainly don't partner left and right.

The stamp image from Swedish Tiger's website does have perf 10.5 on both right and left.

Not an expert, but I suspect that John's stamp has been reperforated on the right side.

You can play around with your image. I noticed the following:

-- the right margin is slightly wider at the bottom, which means IF it was reperforated, the right side would be closer to the original perfs near the bottom (you will see why this is important below)
-- while the stamp is poorly centered, if you copy the top half the stamp DESIGN (not including the margins) and shift it over to the right so that it clears the perforations, you will see that it BARELY clears the perforations, indicating that the total margin is much much smaller than normal (i.e., would almost be touching the design on both sides, unusual but not impossible); IF the stamp was reperforated, this suggests that the "wider" margin was originally much wider
*** if you look at the tips of the bottom 6 teeth on the right side, you will see a light scalloping that shifts in position (it seems to match well with the wider perf 10.5 holes); I think that was the position of the ORIGINAL perforation holes; you don't see it as you move up the right side because the reperforation is slightly crooked (hence the slightly narrower margin as you move up the right side).

Again, not an expert, but those are my observations. I'd be interested in reading what the others see/think.

Building on khj's observations. I made 2 more scans and agree with his conclusion - reperfed on right (in the wrong gauge).

Scan with additional normal stamp to right. Perforations aligned at top. The remnant arcs of the original perforations neatly complete the bottom 4-5 holes.



Same two stamps. Normal (wide) stamp below and trimmed/reperfed stamp on top.



Mystery solved. That was quick. Thanks much.

The mystery remains as to why someone would do this.

No rocket science here. Visually, the right margin appears to be reperforated. The tips of the perforations are too straight and the holes are too clean and round and as pointed out previously, some indications of the previous incumbent perforation 10½ are visible.

The explanation is simple. Besides having too much time on his hands, the person who altered the stamp owned a perf 11 machine, but did not have a perf 10½ machine. While the top and bottom perforations are rotary press 11-70 (spaced 0.070 inches on center), the fake right side perforations are most likely gauge at 11-72 (0.072 spacing), the normal flat plate perforation spacing.

Clark