[oobovril]

Going by Army Service bulletin Y812 Part 1, year 1958, page 19 paragraph 75. The main difference, operationally wise, between the MK.1 and MK.2 valve testers were that the MK.1 had only 18 valve test sockets fitted whereas the MK.2 had 19 with the inclusion here of the type B9A socket. Besides this, other differences between the two MK's was the under slung document tray plus front panel grab rails too being fitted to the MK.2 but not to the MK.1. Also, the MK.1 instrument gauge has red for replace and yellow for good. The MK.2 had green for good on it's gauge. Other notable differences between the two Mk's was that the chicken head knobs on the Circuit selector switch and to that on the Meter selector switch were longer in length on the MK.2., shorter in length on the MK.1. Looking on the web at various images of MK.1's and MK.2's it appeared to me that quite a few MK.1's became modified to include the B9A valve test socket leading to many being designated now as MK.2's but still showing signs of them being the MK.1 due to the other known differences between the two models. Yous thoughts on this?