[sdiy] looking for some pots

[db]

My old Boss mixer uses some cheap slide pots for channel levels. Some are bad.

The service manual lists these as :
ewa-nk6s10a54

(They are 50k 45mm, 30mm throw)

I've checked Alpha and Bournes and Mosuer and Digikey, and I can't find 
anything like it. (45mm with the same pin layout)

Roland is asking silly prices.

Does anyone recognize that number and have any idea who the manufacturer is?
If not, any other pot manufacturers to try?

ANY clues are much appreciated.

Dennis [Los Angeles]