I looked into ordering one of these several months ago.  It would definitely be a valuable tool when repairing the earlier Williams boards, especially the System 3 ~ 7 boards.

I haven't order one as yet, mainly due to the fact I could not locate all the additional parts required from the one supplier.  Please report back with how you go ordering parts etc.

 

exactly my comment - some of those parts will not be easy to track down - but a great tool I  sure.