Picked up a used machine today to refurbish for my shop - everything works - good steam, water out of all the group heads.

Only odd thing is that when the machine is fully warmed up and sitting idle - when the heating element kicks back on the machine restarts itself.. this is only when it goes from sitting warm and element is kicking on.. machine under regular use (heating element being on) I can use the machine as much as I want and will not get this problem.. it's only when sitting... anyone seen anything like this before?

Thanks

How many groups?

Hot connections have higher resistance. Connectors expand and make poor connections when hot.

It's likely there are faulty connections or failing capacitor on a control board. The voltage dip when the element engages after the machine is hot is causing the reset.

Look for discolored wire or connector insulation