The iron is an earthed TCP Weller that I have been using with 100% sucess for many years (about 20 or so). I kept (most of the time) the major comonents connected to their circuit earths. I repeatedly tapped the case or ground points with both hands and the iron tip.

The work bench where I would normally do all this is an earthed bench with a built in mat and grounding to the (earthed) CV system.

Don't forget what I said - if I knacker it in my possession, then I will pay to have it repaired...