Hello mayday.call,
All A/C brakes (AIB and Boeing) should be checked with hydraulic pressure applied and the parking brake set or by somebody on the pedals.
I say , by somebody on the pedals just in case that the brake accumulator is not well charged ...
The "length" of the pins , in fact , the measurement will also depends on the brakes temperature ...
They should be checked when the brakes are cold ...
Usually , the brake should be changed when the pin is flushed to the retaining bracket ... some airlines get a company policy where they changed them before to save some money ...
Look carefully to these pins , it is not really an accurate measurement ...
Hope that clarifies.