[PaulR]

I restored a Cossor 494 several years ago and found that the original valve sockets were not good quality exacerbated by the fact that the radio had been stored in damp conditions. I have also found that the pins on Loctal valves are more troublesome than other types and need to be thoroughly clean to make reliable contact.

In the end I replaced two of the valve holders with better quality ones and it was much more reliable.