A sender unit in milady's Corolla was playing up, - It would choke-rich-mixture but not fast-idle, -and I took it out. Well, tried to.
It was fastened with spline-head machine screws, like an Allen-head but splined. The top of the spline socket had been deliberately crushed in, and the heads were socketed into the casting.
I could cope with the splines, but why did they go to the trouble of crushing!
YOU SHALL NOT REMOVE THIS PART!
Perhaps JohniK can tell me, is it bloody radioactive or something?

(I painstakingly cleaned it with specially-bent brushes and solvents, and it's working again for the moment.)

Froggy is lucky to be ABLE to buy a part for an old appliance.