OK so I guess this could be considered over the top! A batch of 100 ferrite beads arrived today and i have now ordered another 100.
I thought I had used all the 100 up until I found one on the floor.
I have just tested an old EL84 without issues, 230 Va -8 Vg1 with Ia at 35mA so a bit low from the charted 40mA. change to -9 Vg1 gives 28mA so at that working point gm at 7mA/V.
Think I could still use that at on something. Not tested anything using the Octal socket yet as that has no beads on the lines but I will give the old 6P25 another go and see if it causes issues or not, but it will still be getting beads on the leads if it works or not.
Picture attached of present underside wires.
Adrian