Dennis ,
Thank you for your response. All duly noted. Like yourself, never ever had a problem (always a first time so don't tempt fate!).
I normally use infra red lamps but for big bends that complain ( you CAN feel the resistance) I use hot steam for a longer period.
But making sure that moisture is purged afterwards is a pain. The labour time is what the customer NEVER appreciates.
Thank you for your insight.