Hi Gang:
I spoke to my Lexicon buddy and here's what he said (cut-n-pasted below):
"You can try getting support for the MPX500 and the PCM81 at the Lexicon Pro website:
For older stuff -- like the Vortex -- you might need to go to a local mom-and-pop electronics shop. I hear that Jim Fabiano is a good repair guy for old Lexicon gear. His website follows:
Hope this helps. I may check 'em out if my Lexi boxes blow up.