Up for sale here is this line adjust rheostat, removed from a Precise Model 111 tube tester. This is in good shape with light overall wear, and is guaranteed to work. This might work for other models, but I do not know, sorry.
I do not believe this is the original part, since it appears to be dated 1978 and the tube tester was from 1955. This is probably a replacement, but seemed to work fine. It measures around 216.6 ohms on my meter. I have lots of Precise Model 111 parts, just take a look at my other listings, and let me know if you need something that's not listed. Please see my pictures for details.
US shipping and handling is $5, and international is $18. If you have any questions, please ask.
I have more Precise parts and other vintage electronics listed--feel free to take a look! ![](https://rover.ebay.com/roversync/?site=0&stg=1&mpt=1376665199072)