Originally Posted by Tom023
Since there is a leak path for the pressurized air through the ring end gaps, will there be a very tiny amount of air escaping into the crankcase that is slightly audible in the oil filler tube?
Yes. the leakage is through the ring gaps and sometimes between the rings/land interface. You always have a decent amount of air leakage past the rings during a leak down test. This is why they have a standardized air orifice size; To keep everything relative to the leakage expected on an optimal engine.
The rocking at TDC is to help the air pressure to push the rings fully against the lands and mainimize that leakage during the test, which would not occur when the piston is moving, as in normal operation.