can anyone recommend a person in LA area to pay to install a tricky Koetsu cartridge

Like Mike Lavigne said, the only thing that would make a Koetsu "tricky" is that it's hard to see the cantilever and stylus after you've gotten the top surface of the headshell to be plane parallel to the LP surface, which is a good enough starting point for VTA. (In fact, it's a good enough endpoint for VTA, where Koetsu are concerned.). So, have a strong flashlight handy.

This is a good time in history to develop some do it your self skills. Why not look up some videos on YouTube that describe how to install a cartridge? Michael Fremer has several, and I am sure there are others. ( Search for Fremer or Stereophile which may sponsor his videos.) The only thing you will need is a rudimentary tool to set the stylus tip at the right place. There are any number of decent alignment protractors available for well under $100 with which you can do that. Perfection in this process is optional.