Reliable Dealer for 6CS7 tubes

I know this is a well worn and exhausted discussion regarding Leben cs 600 pre- amplifier tubes.  But, I thought I would share my experience searching for this scarce tube.  I have been able to find what I thought were two matched quads from two ebay dealers/sellers.  I sent them to Western Glow Tube Services ( highly recommend BTW) to be tested.  Out of 8 tubes, one was defective and only one "fairly good" quad was identified.  I don't recall where I purchased these tubes but I know one was an EBAY seller and think the other was a fairly well known dealer online.  I have also inquired with Tone Imports and with Leben's US service center regarding the reported pre-amplifier modification; the answer is NO IT IS NOT AVAILABLE.  So, I bring this forward both to alert others of the possibility that those matched quads may not be matched ( or even functional ) and to see if anyone has been able to find a reliable source for the 6CS7.  Lastly, maybe its time to start collectively contacting Tone Imports regarding the need to start modifying our CS 600's.  I wish us all peace and happy listening.