[Plumbicon]

That makes sense... then this corrector was not part of the early versions of the VR1000 and added later ? In the VR1000 user manual the recommended head poles quadrature adjustment is purely mechanical, a rather tedious and cumbersome "trial and error" process involving small adjustments of screws on the head drum to (mechanically) advance or delay the heads position until perfect quadrature was reached. Since it couldn't be done in real time many successive runs were needed and the only control was watching the (recorded) test picture on a monitor after each adjustment.