Hi Alastair, What colour is your 2015? I only ask as I have a 2015S in orange with the A793 chassis in it. and it has it's fair share of faults but it's not been on long enough yet to see whether the overwind packs up
My 2015D is near identical to that 1914 that sold on ebay for daft money yesterday!
Its a grey front with a wooden cabinet....
An update so far--
At 40V and 13W dissipation in the coil, the pitch softened somewhat but was still pretty resistant to removal after an hour.
--I thought,--what the hell, and upped the volts to 50, dissipation to 21W (Probably less since the coil and its resistance being now hot would be somewhat more)--Which if you consider the size of the coil and the mass of the ferrites etc, isnt a Huge amount.....
After about half hour, the pitch was sufficiently soft to remove without excessive force to reveal a fabric bandage-covered doughnut shaped coil. I observed that the pitch was bubbling slowly locally in places, but this got less and less over an hour or so.--I'm assuming that the moisture is vapourising to steam coming to the surface....
There is no burning/hot pitch/insulation smell, just a dusty 'old telly' smell from the coil when up close....
I'm not going to make the coil any hotter than this, I don't think it needs it, although I'll maintain this temp for a couple of hours...
--IF it dies, --well, nothing much lost, it was pretty bad/unusable anyway, and the set itself isnt in great condition!
The pitch is Horrible stuff. Ive taken ages to clean the stuff off my hands. Only thing that seems to shift it easily is 'Brake-Cleaner' I'll not be putting it back on.
I notice that the pitch when cold is very brittle, will chip and crack easily--maybe this is the cause of the issue in the first place!
I will probably coat the coil with a product I have here which motor-rewinders use, called 'Ultimeg' --Supposed to be resistant to moisture and H.V.