@JimAdeny:
I, too, looked for "mod pot" on Ebay. Actually, I found a Bourns 1k/10k concentric pot (article #133006820204, Tek Part n¡ã 311-1411-00).
In the Tek Service Manual the part number is 311-1759-00, and its from Allen-Bradley (not Bourns). Do you think they are interchangeable?
I don't know if they are the same, but I think that product line changed hands a few times, so it's quite possible that they are the same. I'm not familiar with the Tek product you're trying to fix, so I don't know how important it would be to be exactly alike. If they're being sold as Mod Pots, I'd suspect that what you'd be getting would be just a different brand on the backplate. There's no advantage to buying something that also has a Tek part number.
The current maker/vendor is State Electronics (potentiometers.com.) Sounds like you already found their option chart for the Series 70. Then buy a couple of A-B versions off ebay that have the right value pots in them. If the auction shows the OE part number, the Series 70 chart might help you sort out exactly what's in there.
The Mod Pot potentiometers were available in several different tapers as well as reverse tapers, so that's another variable. If you've already taken yours apart, you already know how they are assembled, so you should be able to buy anything with the right resistance (and hope for the right taper), disassemble it and replace your one bad module.
