  NGC4261 (3C270) is an elliptical galaxy containing a 300-parsec scale nuclear
disk of gas and dust imaged by the Hubble Space Telescope (HST), around a
central supermassive black hole. Previous VLBI observations of NGC4261 revealed
a gap in emission in the radio counterjet, presumably due to free-free
absorption in the inner parsec of the accretion disk. Here we present three 8
GHz VLBA observations of NGC4261 that allow us to monitor the location and
depth of the gap, and check for motions in the jet and counterjet. The
separation between the brightest peak and the gap is stable, with an upper
limit to its motion of 0.01 c, supporting the interpretation of the gap as
absorption by an accretion disk rather than an intrinsic jet feature. These
observations span a time of order that required for orbiting material in the
disk to transit the counterjet, so we are able to search for density changes
(clumps) in the disk by monitoring the optical depth of the gap. The optical
depth of the gap is stable to within 20% over 5 years at tau = 1.1 +/- 0.1,
corresponding to an electron density in the disk that is constant to within
10%. We measure an apparent speed in the jet of 0.52 +/- 0.07 c. An apparent
speed could not be measured for the counterjet due to a lack of identifiable
features. From the apparent jet speed and the jet to counterjet brightness
ratio, we calculate the viewing angle of the jet to be 63 +/- 3 degrees and its
intrinsic speed to be 0.46 +/- 0.02 c. From the inclination and position angles
of the parsec-scale radio jet and outer HST disk rotation axis we calculate a
difference between the parsec-scale radio jet and outer HST disk rotation axis
of 12 +/- 2 degrees.
