The company that sold these doesn't seem to have any in stock.  Any suggestions?

What exactly are you after? It was only the 6000 and some later tangentials that had phono preamps. The 4000 never had that option.

I guess he is looking for a suitable RIAA. You can get one from a number of sources - Have a search on eBay or approach one of the re-sellers. About £50 will get you something perfectly decent - you can spend whatever you want though - the cheapest are about £12 - the most expensive £000s!