I went to sand back my daughter's car's roof today to repaint it because the clear coat was peeling.
The DAMN orbital sander was playing up, every time I moved it, it cut out.
I checked and changed the power point I was using, same deal.
So I tried moving the plug in the extension cord.
Every time I moved it, it cut out.

Easy methinks, the cord on the sander is damaged.
Strip down the sander, replaced the cord with a different cord and plug I had in my spares box....all fixed.
Not on your nelly.
Got out the multimeter, the extension cord female plug has an intermittent fault.
It's a solid moulded plug, so no way to repair the plug or even disassemble it to see what's wrong.
Cut off the plug and tested the cord with my multimeter, perfect, no loss all good.
Don't have a spare female plug.

Then I remembered.
The hedge trimmer was exhibiting the same fault a few weeks ago.
Had planned to buy a new one at Xmas.
Grabbed the hedge trimmer, I removed the cord before throwing it out, which woukd have been next weekend.
Reconnected the cord and re-assembled the trimmer.
Works perfectly.

Note to self
I never suspected the extension cord, especially the female end, it's better protected than the male, which can be stepped on.
CHECK EVERYTHING, EVEN THE THINGS THAT WILL NEVER FAIL.

this extension cord is not a cheap cord.
It's double insulated and has a metal sheath protecting the cord from damage.
I will find a way to disassemble the female plug and see what failed.

Had to use the other extension cord, the 15 amp cord.
But got the job done.