[mole42uk]

I don't think you'll ever get results that exactly match the book specification. After all, most valves are old, or they are made on old machines. You don't say where the first two valves are from - are they NOS, pulls or something else? If the Russian ones are overheating, have you checked all the voltages at, and connections to, the socket? Do you have ferrite snubbers on the wires connecting all the sockets - it has been known for valves to go into high-frequency oscillation on the Sussex tester, indeed on many testers there is that possibility....there are comments on this somewhere on this thread, I know it's a pain to read through though!