[Bobn]

I've just picked up this rusty Vigor, amongst the catalogue of woes is that the dipstick can't be unscrewed when the oil is hot. When cold it unscrews easily enough.
Has anyone else had this problem?
I was thinking of dressing the threads a bit to slightly reduce the O/D, but I'm puzzled as to what has caused the problem.

 

[Windmill John]

I cannot remember from my old Vigor if it is different to my Dommie; ie still plastic.
If so, it does deform and whenever I found it tight, I would make sure I got a balanced grip to ensure not to break it.
You do see quite a few broken ones. If the tangs break off, you can always order a new one and remove the old with big pliers, moles, etc.