Folkard states:
State 1 – East side weak; letters normal.
State 2 – East and west networks slightly thinned; Postage slightly compressed; Value compressed; E slightly thinner.
I have two copies, the first (173 EB) in the plum range of colours which would make it contemporary with plate 180 or thereabouts, and (173 EB a) a worn decidedly orange copy which would put it with the later 180s. Both of these appear to be state 2, though the descriptions given by Folkard leaves me with a question mark.
The only state 1 I have access to is the damaged imprimatur which would appear to have weak east and west sides. With both of the state 2 examples, both sides of the stamp appear to be stronger. Rather than the E being slightly thinner, I would argue that it has been re-cut, with the middle cross bar changing it's character and the lower left serif being extended. There may be hints of some doubling, or rather thickening of the corner frames, but the repair appears to be very nearly coincident.
Perhaps Folkard was describing a state 2, and these two examples are in fact state 3s. Alternatively I could have got the plating wrong with 174 seems closest, but the B is wrong.
Imprimatur