I just bought a Steel Jaeger LeCoultre, case reference E501 with movement 497 and movement serial number 1.068.745.
Although te dial shows pretty much discolouration, the movement looks very clean and well kept. All functions work well and the watch keeps time very well. The rotor moves well, but is quite noisy when bumping against the moment at the end of its arc. It makes a metallic sound when hitting the side of the movement were the L shaped tooth bearing Lever (9528) is mounted. I took the banking stip spring (1472) out. It seemed in good shape, but when I compared the model with the part as described in your book (some years ago I bought nr. 260 out of the 500 signed by you) at page 166, I noticed that the modified piece for cal. 497/1 (as shown on page 167 of your book) was mounted.
Do you know if the modified banking stop spring of cal. 497/1 does fit in a 497 movement? I consider searching for a banking stop spring according to the specifications of cal. 497, however it would be useless if the modified spring also fits the cal. 497.
I am looking forward to hearing from you.