Hi, are you really sure, that the video heads are defect? I have had now several hundred VX recorders for repair and only 2 of around 600 had defect video heads... and i still have some dozen used and new drives on stock. The last price for a brand new videohead was around 230 Euro... if you really need a video head, here in Bogen/Germany are still some available :) Of course not sooo expensive...;)
That what looks like a worn/defect head are leaking eloctrolythic capacitors on the upper mainboard... there are around 120 of them in a VX recorder who need urgent replacement.