Hey Archie. These look the ones I have.
https://www.hificollective.co.uk/potentiometers/tkd-potentiometer.htmlhttps://www.partsconnexion.com/TKD-64187.htmlNot sure who else might carry it, but I like to use these two companies among others.
Even though partsconnexion has good sales going a lot, sometimes pound/dollar changes cause HiFi to be a good value. They have a really good collection of "curated" stuff, and some things I can't find elsewhere. Likely to have everything else I might want at the time, and liking to make up orders with more parts to spread the shipping, I buy from them pretty often. Pretty fast shipping times too considering the distance (pre covid anyway).
Finding clear wiring diagrams for the TDK in English was difficult for me. So I looked inside mine and this is how it goes.
A Caution: When I first started working in there, years ago, forgetting one time to double check by manually draining caps once the pre was opened, the front headphone-out caps were still charged...that was a nasty learning experience. So if you haven't already, I would check out how to drain the caps safely to be sure you don't get an unexpected zap! And if you ever go into the ZMA, you may not be working directly on caps, but you can still become the connector between power and ground...gives me shivers thinking what that power supply charged could do.
With the pre open, parts facing up for access, the bottom of the volume pot is then close to you, and the top, with the adjuster, is away, going through the amp plate. From this perspective, there are two pairs of three solder tabs, top and bottom.
Not sure this is the best, but I chose to install it putting those tabs to my right as I look from the CSP3 front and bottom. This orientation made it pretty close between the channel switch and input pots, just enough room for small spaces. Probably not necessary, but for good measure, I decided to wrap some teflon tape around the sides toward the amp plate to be sure there could be no connection or vibration between adjacent parts.
The three solder tabs closest to the pot bottom (top from this view) are the left channel, and the ones closer to the amp plate are the right.
The ground is marked "C" and you can easily connect channel grounds (top and bottom) with a wire soldering them together, while soldering the ground wires proper to the easier to access "top" connector. Steve may have his set up so that one ground wire is stripped longer, and strung through the top connector, long enough to solder to the top and bottom with one wire. Everywhere I make sure I have a good mechanical connection as I solder.
Next to C, in the middle, is 2. These are the pot outputs going to the tubes, mine via the input pots.
Then "1" are the pot inputs, wired to the channel switch.
Hope this helps.
Will